diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5983ae2..ad64c2d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- Added `reinstall` parameter to micropip.install to allow reinstalling
+  a package that is already installed
+  [#64](https://github.com/pyodide/micropip/pull/64)
+
 ### Fixed
 
 - micropip now respects the `yanked` flag in the PyPI Simple API.
diff --git a/micropip/install.py b/micropip/install.py
new file mode 100644
index 0000000..b2927c9
--- /dev/null
+++ b/micropip/install.py
@@ -0,0 +1,125 @@
+import asyncio
+import importlib
+from pathlib import Path
+
+from ._compat import loadPackage, to_js
+from ._vendored.packaging.src.packaging.markers import default_environment
+from .constants import FAQ_URLS
+from .logging import indent_log, setup_logging
+from .transaction import Transaction
+from .uninstall import uninstall_distributions
+
+
+async def install(
+    requirements: str | list[str],
+    index_urls: list[str] | str,
+    keep_going: bool = False,
+    deps: bool = True,
+    credentials: str | None = None,
+    pre: bool = False,
+    *,
+    constraints: list[str] | None = None,
+    reinstall: bool = False,
+    verbose: bool | int | None = None,
+) -> None:
+    with setup_logging().ctx_level(verbose) as logger:
+
+        ctx = default_environment()
+        if isinstance(requirements, str):
+            requirements = [requirements]
+
+        fetch_kwargs = {}
+
+        if credentials:
+            fetch_kwargs["credentials"] = credentials
+
+        # Note: getsitepackages is not available in a virtual environment...
+        # See https://github.com/pypa/virtualenv/issues/228 (issue is closed but
+        # problem is not fixed)
+        from site import getsitepackages
+
+        wheel_base = Path(getsitepackages()[0])
+
+        transaction = Transaction(
+            ctx=ctx,  # type: ignore[arg-type]
+            ctx_extras=[],
+            keep_going=keep_going,
+            deps=deps,
+            pre=pre,
+            fetch_kwargs=fetch_kwargs,
+            verbose=verbose,
+            index_urls=index_urls,
+            constraints=constraints,
+            reinstall=reinstall,
+        )
+        await transaction.gather_requirements(requirements)
+
+        if transaction.failed:
+            failed_requirements = ", ".join([f"'{req}'" for req in transaction.failed])
+            raise ValueError(
+                f"Can't find a pure Python 3 wheel for: {failed_requirements}\n"
+                f"See: {FAQ_URLS['cant_find_wheel']}\n"
+            )
+
+        pyodide_packages, wheels = transaction.pyodide_packages, transaction.wheels
+
+        packages_all = [pkg.name for pkg in wheels + pyodide_packages]
+        distributions = search_installed_packages(packages_all)
+
+        with indent_log():
+            uninstall_distributions(distributions, logger)
+
+        logger.debug(
+            "Installing packages %r and wheels %r ",
+            transaction.pyodide_packages,
+            [w.filename for w in transaction.wheels],
+        )
+
+        if packages_all:
+            logger.info("Installing collected packages: %s", ", ".join(packages_all))
+
+        # Install PyPI packages
+        # detect whether the wheel metadata is from PyPI or from custom location
+        # wheel metadata from PyPI has SHA256 checksum digest.
+        await asyncio.gather(*(wheel.install(wheel_base) for wheel in wheels))
+
+        # Install built-in packages
+        if pyodide_packages:
+            # Note: branch never happens in out-of-browser testing because in
+            # that case REPODATA_PACKAGES is empty.
+            await asyncio.ensure_future(
+                loadPackage(to_js([name for [name, _, _] in pyodide_packages]))
+            )
+
+        packages = [f"{pkg.name}-{pkg.version}" for pkg in pyodide_packages + wheels]
+
+        if packages:
+            logger.info("Successfully installed %s", ", ".join(packages))
+
+        importlib.invalidate_caches()
+
+
+def search_installed_packages(
+    names: list[str],
+) -> list[importlib.metadata.Distribution]:
+    """
+    Get installed packages by name.
+
+    Parameters
+    ----------
+    names
+        List of distribution names to search for.
+
+    Returns
+    -------
+    List of distributions that were found.
+    If a distribution is not found, it is not included in the list.
+    """
+    distributions = []
+    for name in names:
+        try:
+            distributions.append(importlib.metadata.distribution(name))
+        except importlib.metadata.PackageNotFoundError:
+            pass
+
+    return distributions
diff --git a/micropip/package_manager.py b/micropip/package_manager.py
index 0ad6fda..56bdab7 100644
--- a/micropip/package_manager.py
+++ b/micropip/package_manager.py
@@ -2,6 +2,8 @@
 import builtins
 import importlib
 import importlib.metadata
+import logging
+from collections.abc import Iterable
 from importlib.metadata import Distribution
 from pathlib import Path
 from typing import (  # noqa: UP035 List import is necessary due to the `list` method
@@ -14,7 +16,7 @@
 from ._vendored.packaging.src.packaging.markers import default_environment
 from .constants import FAQ_URLS
 from .freeze import freeze_lockfile
-from .logging import setup_logging
+from .logging import indent_log, setup_logging
 from .package import PackageDict, PackageMetadata
 from .transaction import Transaction
 
@@ -48,6 +50,7 @@ async def install(
         index_urls: list[str] | str | None = None,
         *,
         constraints: list[str] | None = None,
+        reinstall: bool = False,
         verbose: bool | int | None = None,
     ) -> None:
         """Install the given package and all of its dependencies.
@@ -140,6 +143,16 @@ async def install(
             Unlike ``requirements``, the package name _must_ be provided in the
             PEP-508 format e.g. ``pkgname@https://...``.
 
+        reinstall:
+
+            If ``False`` (default), micropip will show an error if the requested package
+            is already installed, but with a incompatible version. If ``True``,
+            micropip will uninstall the existing packages that are not compatible with
+            the requested version and install the packages again.
+
+            Note that packages that are already imported will not be reloaded, so make
+            sure to reload the module after reinstalling by e.g. running importlib.reload(module).
+
         verbose:
             Print more information about the process. By default, micropip does not
             change logger level. Setting ``verbose=True`` will print similar
@@ -179,6 +192,7 @@ async def install(
                 verbose=verbose,
                 index_urls=index_urls,
                 constraints=constraints,
+                reinstall=reinstall,
             )
             await transaction.gather_requirements(requirements)
 
@@ -193,7 +207,15 @@ async def install(
 
             pyodide_packages, wheels = transaction.pyodide_packages, transaction.wheels
 
-            package_names = [pkg.name for pkg in wheels + pyodide_packages]
+            packages_all = [pkg.name for pkg in wheels + pyodide_packages]
+
+            distributions = search_installed_packages(packages_all)
+            # This check is redundant because the distributions will always be an emtpy list when reinstall==False
+            # (no installed packages will be returned from transaction)
+            # But just in case.
+            if reinstall:
+                with indent_log():
+                    self._uninstall_distributions(distributions, logger)
 
             logger.debug(
                 "Installing packages %r and wheels %r ",
@@ -201,9 +223,9 @@ async def install(
                 [w.filename for w in transaction.wheels],
             )
 
-            if package_names:
+            if packages_all:
                 logger.info(
-                    "Installing collected packages: %s", ", ".join(package_names)
+                    "Installing collected packages: %s", ", ".join(packages_all)
                 )
 
             # Install PyPI packages
@@ -422,68 +444,7 @@ def uninstall(
                 except importlib.metadata.PackageNotFoundError:
                     logger.warning("Skipping '%s' as it is not installed.", package)
 
-            for dist in distributions:
-                # Note: this value needs to be retrieved before removing files, as
-                #       dist.name uses metadata file to get the name
-                name = dist.name
-                version = dist.version
-
-                logger.info("Found existing installation: %s %s", name, version)
-
-                root = get_root(dist)
-                files = get_files_in_distribution(dist)
-                directories = set()
-
-                for file in files:
-                    if not file.is_file():
-                        if not file.is_relative_to(root):
-                            # This file is not in the site-packages directory. Probably one of:
-                            # - data_files
-                            # - scripts
-                            # - entry_points
-                            # Since we don't support these, we can ignore them (except for data_files (TODO))
-                            logger.warning(
-                                "skipping file '%s' that is relative to root",
-                            )
-                            continue
-                        # see PR 130, it is likely that this is never triggered since Python 3.12
-                        # as non existing files are not listed by get_files_in_distribution anymore.
-                        logger.warning(
-                            "A file '%s' listed in the metadata of '%s' does not exist.",
-                            file,
-                            name,
-                        )
-
-                        continue
-
-                    file.unlink()
-
-                    if file.parent != root:
-                        directories.add(file.parent)
-
-                # Remove directories in reverse hierarchical order
-                for directory in sorted(
-                    directories, key=lambda x: len(x.parts), reverse=True
-                ):
-                    try:
-                        directory.rmdir()
-                    except OSError:
-                        logger.warning(
-                            "A directory '%s' is not empty after uninstallation of '%s'. "
-                            "This might cause problems when installing a new version of the package. ",
-                            directory,
-                            name,
-                        )
-
-                if hasattr(self.compat_layer.loadedPackages, name):
-                    delattr(self.compat_layer.loadedPackages, name)
-                else:
-                    # This should not happen, but just in case
-                    logger.warning(
-                        "a package '%s' was not found in loadedPackages.", name
-                    )
-
-                logger.info("Successfully uninstalled %s-%s", name, version)
+            self._uninstall_distributions(distributions, logger)
 
             importlib.invalidate_caches()
 
@@ -524,3 +485,109 @@ def set_constraints(self, constraints: List[str]):  # noqa: UP006
         """
 
         self.constraints = constraints[:]
+
+    def _uninstall_distributions(
+        self,
+        distributions: Iterable[Distribution],
+        logger: logging.Logger,  # TODO: move this to an attribute of the PackageManager
+    ) -> None:
+        """
+        Uninstall the given package distributions.
+
+        This function does not do any checks, so make sure that the distributions
+        are installed and that they are installed using a wheel file, i.e. packages
+        that have distribution metadata.
+
+        This function also does not invalidate the import cache, so make sure to
+        call `importlib.invalidate_caches()` after calling this function.
+
+        Parameters
+        ----------
+        distributions
+            Package distributions to uninstall.
+
+        """
+        for dist in distributions:
+            # Note: this value needs to be retrieved before removing files, as
+            #       dist.name uses metadata file to get the name
+            name = dist.name
+            version = dist.version
+
+            logger.info("Found existing installation: %s %s", name, version)
+
+            root = get_root(dist)
+            files = get_files_in_distribution(dist)
+            directories = set()
+
+            for file in files:
+                if not file.is_file():
+                    if not file.is_relative_to(root):
+                        # This file is not in the site-packages directory. Probably one of:
+                        # - data_files
+                        # - scripts
+                        # - entry_points
+                        # Since we don't support these, we can ignore them (except for data_files (TODO))
+                        logger.warning(
+                            "skipping file '%s' that is relative to root",
+                        )
+                        continue
+                    # see PR 130, it is likely that this is never triggered since Python 3.12
+                    # as non existing files are not listed by get_files_in_distribution anymore.
+                    logger.warning(
+                        "A file '%s' listed in the metadata of '%s' does not exist.",
+                        file,
+                        name,
+                    )
+
+                    continue
+
+                file.unlink()
+
+                if file.parent != root:
+                    directories.add(file.parent)
+
+            # Remove directories in reverse hierarchical order
+            for directory in sorted(
+                directories, key=lambda x: len(x.parts), reverse=True
+            ):
+                try:
+                    directory.rmdir()
+                except OSError:
+                    logger.warning(
+                        "A directory '%s' is not empty after uninstallation of '%s'. "
+                        "This might cause problems when installing a new version of the package. ",
+                        directory,
+                        name,
+                    )
+
+            if hasattr(self.compat_layer.loadedPackages, name):
+                delattr(self.compat_layer.loadedPackages, name)
+            else:
+                # This should not happen, but just in case
+                logger.warning("a package '%s' was not found in loadedPackages.", name)
+
+            logger.info("Successfully uninstalled %s-%s", name, version)
+
+
+def search_installed_packages(
+    names: list[str],
+) -> list[importlib.metadata.Distribution]:
+    """
+    Get installed packages by name.
+    Parameters
+    ----------
+    names
+        List of distribution names to search for.
+    Returns
+    -------
+    List of distributions that were found.
+    If a distribution is not found, it is not included in the list.
+    """
+    distributions = []
+    for name in names:
+        try:
+            distributions.append(importlib.metadata.distribution(name))
+        except importlib.metadata.PackageNotFoundError:
+            pass
+
+    return distributions
diff --git a/micropip/transaction.py b/micropip/transaction.py
index db32665..0443a51 100644
--- a/micropip/transaction.py
+++ b/micropip/transaction.py
@@ -45,6 +45,7 @@ class Transaction:
 
     verbose: bool | int | None = None
     constraints: list[str] | None = None
+    reinstall: bool = False
 
     def __post_init__(self) -> None:
         # If index_urls is None, pyodide-lock.json have to be searched first.
@@ -94,7 +95,22 @@ async def add_requirement(self, req: str | Requirement) -> None:
 
         return await self.add_requirement_inner(Requirement(req))
 
-    def check_version_satisfied(self, req: Requirement) -> tuple[bool, str]:
+    def check_version_satisfied(
+        self, req: Requirement, *, allow_reinstall: bool = False
+    ) -> tuple[bool, str]:
+        """
+        Check if the installed version of a package satisfies the requirement.
+        Returns True if the requirement is satisfied, False otherwise.
+
+        Parameters
+        ----------
+        req
+            The requirement to check.
+
+        allow_reinstall
+            If False, this function will raise exception if the package is already installed
+            and the installed version does not satisfy the requirement.
+        """
         ver = None
         try:
             ver = importlib.metadata.version(req.name)
@@ -110,9 +126,16 @@ def check_version_satisfied(self, req: Requirement) -> tuple[bool, str]:
             # installed version matches, nothing to do
             return True, ver
 
-        raise ValueError(
-            f"Requested '{req}', " f"but {req.name}=={ver} is already installed"
-        )
+        if allow_reinstall:
+            return False, ""
+        else:
+            raise ValueError(
+                f"Requested '{req}', "
+                f"but {req.name}=={ver} is already installed. "
+                "If you want to reinstall the package with a different version, "
+                "use micropip.install(..., reinstall=True) to force reinstall, "
+                "or micropip.uninstall(...) to uninstall the package first."
+            )
 
     async def add_requirement_inner(
         self,
@@ -169,7 +192,10 @@ def eval_marker(e: dict[str, str]) -> bool:
         # Is some version of this package is already installed?
         req.name = canonicalize_name(req.name)
 
-        satisfied, ver = self.check_version_satisfied(req)
+        satisfied, ver = self.check_version_satisfied(
+            req, allow_reinstall=self.reinstall
+        )
+
         if satisfied:
             logger.info("Requirement already satisfied: %s (%s)", req, ver)
             return
@@ -251,7 +277,9 @@ async def _add_requirement_from_package_index(self, req: Requirement):
 
         # Maybe while we were downloading pypi_json some other branch
         # installed the wheel?
-        satisfied, ver = self.check_version_satisfied(req)
+        satisfied, ver = self.check_version_satisfied(
+            req, allow_reinstall=self.reinstall
+        )
         if satisfied:
             logger.info("Requirement already satisfied: %s (%s)", req, ver)
 
diff --git a/micropip/uninstall.py b/micropip/uninstall.py
new file mode 100644
index 0000000..3ebc8e3
--- /dev/null
+++ b/micropip/uninstall.py
@@ -0,0 +1,108 @@
+import importlib
+import importlib.metadata
+import logging
+from collections.abc import Iterable
+from importlib.metadata import Distribution
+
+from ._compat import loadedPackages
+from ._utils import get_files_in_distribution, get_root
+from .logging import setup_logging
+
+
+def uninstall(packages: str | list[str], *, verbose: bool | int = False) -> None:
+    with setup_logging().ctx_level(verbose) as logger:
+
+        if isinstance(packages, str):
+            packages = [packages]
+
+        distributions: list[Distribution] = []
+        for package in packages:
+            try:
+                dist = importlib.metadata.distribution(package)
+                distributions.append(dist)
+            except importlib.metadata.PackageNotFoundError:
+                logger.warning("Skipping '%s' as it is not installed.", package)
+
+        uninstall_distributions(distributions, logger)
+
+        importlib.invalidate_caches()
+
+
+def uninstall_distributions(
+    distributions: Iterable[Distribution],
+    logger: logging.Logger,  # TODO: move this to an attribute of the PackageManager
+) -> None:
+    """
+    Uninstall the given package distributions.
+
+    This function does not do any checks, so make sure that the distributions
+    are installed and that they are installed using a wheel file, i.e. packages
+    that have distribution metadata.
+
+    This function also does not invalidate the import cache, so make sure to
+    call `importlib.invalidate_caches()` after calling this function.
+
+    Parameters
+    ----------
+    distributions
+        Package distributions to uninstall.
+
+    """
+    for dist in distributions:
+        # Note: this value needs to be retrieved before removing files, as
+        #       dist.name uses metadata file to get the name
+        name = dist.name
+        version = dist.version
+
+        logger.info("Found existing installation: %s %s", name, version)
+
+        root = get_root(dist)
+        files = get_files_in_distribution(dist)
+        directories = set()
+
+        for file in files:
+            if not file.is_file():
+                if not file.is_relative_to(root):
+                    # This file is not in the site-packages directory. Probably one of:
+                    # - data_files
+                    # - scripts
+                    # - entry_points
+                    # Since we don't support these, we can ignore them (except for data_files (TODO))
+                    logger.warning(
+                        "skipping file '%s' that is relative to root",
+                    )
+                    continue
+                # see PR 130, it is likely that this is never triggered since Python 3.12
+                # as non existing files are not listed by get_files_in_distribution anymore.
+                logger.warning(
+                    "A file '%s' listed in the metadata of '%s' does not exist.",
+                    file,
+                    name,
+                )
+
+                continue
+
+            file.unlink()
+
+            if file.parent != root:
+                directories.add(file.parent)
+
+        # Remove directories in reverse hierarchical order
+        for directory in sorted(directories, key=lambda x: len(x.parts), reverse=True):
+            try:
+                directory.rmdir()
+            except OSError:
+                logger.warning(
+                    "A directory '%s' is not empty after uninstallation of '%s'. "
+                    "This might cause problems when installing a new version of the package. ",
+                    directory,
+                    name,
+                )
+
+        if hasattr(loadedPackages, name):
+            delattr(loadedPackages, name)
+        else:
+            # This should not happen, but just in case
+            logger.warning("a package '%s' was not found in loadedPackages.", name)
+
+        logger.info("Successfully uninstalled %s-%s", name, version)
diff --git a/tests/integration/test_integration.py b/tests/integration/test_integration.py
index 79d1cb6..12a5d55 100644
--- a/tests/integration/test_integration.py
+++ b/tests/integration/test_integration.py
@@ -52,6 +52,41 @@ async def _run(selenium):
     _run(selenium_standalone_micropip)
 
 
+@integration_test_only
+def test_integration_install_reinstall(selenium_standalone_micropip, pytestconfig):
+    @run_in_pyodide
+    async def _run(selenium):
+        import micropip
+
+        await micropip.install("mccabe==0.6.1")
+
+        import mccabe
+
+        assert mccabe.__version__ == "0.6.1"
+
+        try:
+            await micropip.install("mccabe==0.7.0", reinstall=False)
+        except ValueError as e:
+            assert "already installed" in str(e)
+        else:
+            raise Exception("Should raise!")
+
+        await micropip.install("mccabe==0.7.0", reinstall=True)
+
+        import mccabe
+
+        # still 0.6.1
+        assert mccabe.__version__ == "0.6.1"
+
+        import importlib
+
+        importlib.reload(mccabe)
+
+        assert mccabe.__version__ == "0.7.0"
+
+    _run(selenium_standalone_micropip)
+
+
 @integration_test_only
 def test_integration_install_yanked(selenium_standalone_micropip, pytestconfig):
     @run_in_pyodide
diff --git a/tests/test_install.py b/tests/test_install.py
index af8dae2..64baba1 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -448,3 +448,31 @@ async def run(selenium, numpy_url, shapely_url):
         Point(0, 0)
 
     run(selenium, numpy_wheel.url, shapely_wheel.url)
+
+
+@pytest.mark.asyncio
+async def test_reinstall_different_version(
+    mock_fetch: mock_fetch_cls,
+    mock_importlib,
+) -> None:
+    import importlib.metadata
+
+    import pytest
+
+    dummy = "dummy"
+    version_old = "1.0.0"
+    version_new = "2.0.0"
+
+    mock_fetch.add_pkg_version(dummy, version_old)
+    mock_fetch.add_pkg_version(dummy, version_new)
+
+    await micropip.install(f"{dummy}=={version_new}")
+    assert micropip.list()[dummy].version == version_new
+    assert importlib.metadata.version(dummy) == version_new
+
+    with pytest.raises(ValueError, match="already installed"):
+        await micropip.install(f"{dummy}=={version_old}", reinstall=False)
+
+    await micropip.install(f"{dummy}=={version_old}", reinstall=True)
+    assert micropip.list()[dummy].version == version_old
+    assert importlib.metadata.version(dummy) == version_old