diff --git a/Gemfile b/Gemfile
index 1ea1cccf3..32cb0279d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,6 +5,7 @@ gem "rails", "7.2.2"
 gem "aws-sdk-s3"
 gem "bootsnap", require: false
 gem "bunny"
+gem "content_block_tools"
 gem "dalli"
 gem "fuzzy_match"
 gem "gds-api-adapters"
diff --git a/Gemfile.lock b/Gemfile.lock
index 24dcc708f..37513c62f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -119,6 +119,8 @@ GEM
     climate_control (1.2.0)
     concurrent-ruby (1.3.4)
     connection_pool (2.4.1)
+    content_block_tools (0.2.0)
+      actionview (= 7.2.2)
     crack (1.0.0)
       bigdecimal
       rexml
@@ -868,6 +870,7 @@ DEPENDENCIES
   bunny
   byebug
   climate_control
+  content_block_tools
   dalli
   database_cleaner
   factory_bot_rails
diff --git a/app/presenters/content_embed_presenter.rb b/app/presenters/content_embed_presenter.rb
index 7774bb609..f8ee89fb2 100644
--- a/app/presenters/content_embed_presenter.rb
+++ b/app/presenters/content_embed_presenter.rb
@@ -64,14 +64,13 @@ def render_embedded_editions(content)
       content
     end
 
-    # This is a temporary solution to get email address content blocks working
-    # while we agree on a long-term approach that works for everything.
     def get_content_for_edition(edition)
-      if edition.document_type == "content_block_email_address"
-        edition.details[:email_address]
-      else
-        edition.title
-      end
+      ContentBlockTools::ContentBlock.new(
+        document_type: edition.document_type,
+        content_id: edition.document.content_id,
+        title: edition.title,
+        details: edition.details,
+      ).render
     end
   end
 end
diff --git a/app/services/embedded_content_finder_service.rb b/app/services/embedded_content_finder_service.rb
index f56a91643..1c334b498 100644
--- a/app/services/embedded_content_finder_service.rb
+++ b/app/services/embedded_content_finder_service.rb
@@ -1,10 +1,4 @@
 class EmbeddedContentFinderService
-  ContentReference = Data.define(:document_type, :content_id, :embed_code)
-
-  SUPPORTED_DOCUMENT_TYPES = %w[contact content_block_email_address].freeze
-  UUID_REGEX = /([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})/
-  EMBED_REGEX = /({{embed:(#{SUPPORTED_DOCUMENT_TYPES.join('|')}):#{UUID_REGEX}}})/
-
   def fetch_linked_content_ids(details, locale)
     content_references = details.values.map { |value|
       find_content_references(value)
@@ -21,7 +15,7 @@ def find_content_references(value)
     when Hash
       value.map { |_, v| find_content_references(v) }.flatten.uniq
     when String
-      value.scan(EMBED_REGEX).map { |match| ContentReference.new(document_type: match[1], content_id: match[2], embed_code: match[0]) }
+      ContentBlockTools::ContentBlockReference.find_all_in_document(value)
     else
       []
     end
diff --git a/docs/arch/adr-007-move-content-block-rendering-logic-to-external-gem.md b/docs/arch/adr-007-move-content-block-rendering-logic-to-external-gem.md
new file mode 100644
index 000000000..16d9cda54
--- /dev/null
+++ b/docs/arch/adr-007-move-content-block-rendering-logic-to-external-gem.md
@@ -0,0 +1,92 @@
+# Decision Record: Move Content Block rendering logic to external gem
+
+## Context
+
+Content blocks within Publishing API are a relatively new concept, that mainly sits with the Content
+Modelling Team. Whilst still in development, the basic concept is that a publishing user will be able
+to embed a "block" of reusable content within a document, and it will then be rendered within the 
+document on publication. When the content of the block changes, all pages that use the block will 
+change to show the latest information.
+
+When a piece of content that uses a content block (or content blocks) is sent to the publishing API,
+we first scan over each field within the content to find embed codes, which currently look like this:
+
+```markdown
+{{embed:$embed_type:$uuid}}
+```
+
+Where `$embed_type` is the type of content to be embedded and `$uuid` is the content ID of the content
+block.
+
+If there are any embed codes found, these are added as "links" to the content within Publishing API
+([See here for more information about links and link expansion](https://github.com/alphagov/publishing-api/blob/main/docs/link-expansion.md)).
+
+When the piece of content is sent to the Content Store (either draft or live), we scan the content
+again for embed codes, and replace the embed code with the actual content block content.
+
+At the moment, this is fairly simple, contacts are replaced with the Title (as contacts work is
+still a work in progress) and email addresses are replaced with the email. However, as this work
+progresses, it is envisioned that embedded content rendering will get significantly more complex.
+
+Additionally, there are places where we need access to the embed logic outside of Publishing API:
+
+### Whitehall Live Preview
+
+At the moment, when a user clicks on "Preview" within Whitehall, it takes the content from the 
+body field, and  uses the Govspeak gem (and some additional Whitehall-specific logic) to 
+render the Govspeak.
+
+Currently, Whitehall or Govspeak does not understand the embed code, so embed codes are left
+untouched:
+
+![Whitehall editor body field showing link to preview button](./images/live-preview-1.png)
+
+![Live preview showing embed code left inplace](./images/live-preview-2.png)
+
+We therefore need a way to handle the embed codes within live preview
+
+### "In-app" preview within Content Block Manager
+
+When editors are making changes to content blocks within the Content Block Manager, it's important
+for users to be able to see the changes they make within the context of the pages that use the
+blocks.
+
+We can't use the existing draft stack because:
+
+a) We want to show the content block changes in the context of the live documents; and
+b) Publishing content block changes to the draft stack could cause confusion when a user
+is previewing the changes to their own content and seeing unpublished changes to a content block
+
+With this in mind, we are proposing that we fetch the HTML of live content and then run a 
+find/replace against the HTML of a content block with the HTML of the current draft, then rendering
+this HTML within our app.
+
+Both of these solutions require each application having knowledge of how a content block will be
+rendered.
+
+Initially we considered having an API endpoint within Publishing API to "preview" a content block.
+However, this was discounted because:
+
+a) We run the risk of overloading the Publishing API with extra API endpoints
+b) There is not much rendering logic in Publishing API itself, and logic will potentially get more
+complex as content blocks evolve
+c) If there are a number of content blocks within a page, this may cause a performance issues when
+making multiple calls to an API
+
+## Decisions
+
+We are proposing moving the Content Block rendering and parsing logic to a new [content_block_tools gem](https://github.com/alphagov/content_block_tools)
+
+This will give a single source of truth for how content blocks are rendered, which can be easily pulled
+into other applications.
+
+## Consequences
+
+Once the work to move the logic into the gem is approved, we will then need to add content_block_tools as
+a dependency in Publishing API to ensure the gem is the only source of truth. 
+
+We will then be able to carry out the two pieces of work as detailed above. They are both contained within
+the Whitehall application, which already has govuk_publishing_components as a dependency.
+
+One possible downside is we will need to release a new version of a gem and ensure it is used in each application
+when a change occurs, but as we don't expect to be making changes regularly, we believe this risk is minimal.
diff --git a/docs/arch/images/live-preview-1.png b/docs/arch/images/live-preview-1.png
new file mode 100644
index 000000000..825781bc0
Binary files /dev/null and b/docs/arch/images/live-preview-1.png differ
diff --git a/docs/arch/images/live-preview-2.png b/docs/arch/images/live-preview-2.png
new file mode 100644
index 000000000..f7650715d
Binary files /dev/null and b/docs/arch/images/live-preview-2.png differ
diff --git a/spec/integration/put_content/content_with_embedded_content_spec.rb b/spec/integration/put_content/content_with_embedded_content_spec.rb
index 0a77cf0d6..58e0c9fac 100644
--- a/spec/integration/put_content/content_with_embedded_content_spec.rb
+++ b/spec/integration/put_content/content_with_embedded_content_spec.rb
@@ -22,7 +22,7 @@
     it "should send transformed content to the content store" do
       put "/v2/content/#{content_id}", params: payload.to_json
 
-      expect_content_store_to_have_received_details_including({ "body" => "#{first_contact.title} #{second_contact.title}" })
+      expect_content_store_to_have_received_details_including({ "body" => "#{presented_details_for(first_contact)} #{presented_details_for(second_contact)}" })
     end
   end
 
@@ -52,7 +52,7 @@
     it "should send transformed content to the content store" do
       put "/v2/content/#{content_id}", params: payload_for_multiple_field_embeds.to_json
 
-      expect_content_store_to_have_received_details_including({ "downtime_message" => first_contact.title.to_s })
+      expect_content_store_to_have_received_details_including({ "downtime_message" => presented_details_for(first_contact) })
     end
   end
 
@@ -128,11 +128,11 @@
             "body" => [
               {
                 "content_type" => "text/govspeak",
-                "content" => first_contact.title,
+                "content" => presented_details_for(first_contact),
               },
               {
                 "content_type" => "text/html",
-                "content" => "<p>#{first_contact.title}</p>",
+                "content" => "<p>#{presented_details_for(first_contact)}</p>",
               },
             ],
           },
@@ -142,11 +142,11 @@
             "body" => [
               {
                 "content_type" => "text/govspeak",
-                "content" => second_contact.title,
+                "content" => presented_details_for(second_contact),
               },
               {
                 "content_type" => "text/html",
-                "content" => "<p>#{second_contact.title}</p>",
+                "content" => "<p>#{presented_details_for(second_contact)}</p>",
               },
             ],
           },
@@ -176,32 +176,7 @@
     it "should send transformed content to the content store" do
       put "/v2/content/#{content_id}", params: payload.to_json
 
-      expect_content_store_to_have_received_details_including({ "body" => array_including({ "content_type" => "text/govspeak", "content" => "#{first_contact.title} #{second_contact.title}" }) })
-    end
-  end
-
-  context "with an embedded email address" do
-    let(:first_email_address) { create(:edition, state: "published", content_store: "live", document_type: "content_block_email_address", details: { email_address: "foo@example.com" }) }
-    let(:second_email_address) { create(:edition, state: "published", content_store: "live", document_type: "content_block_email_address", details: { email_address: "bar@example.com" }) }
-    let(:document) { create(:document, content_id:) }
-
-    before do
-      payload.merge!(document_type: "press_release", schema_name: "news_article", details: { body: "{{embed:content_block_email_address:#{first_email_address.document.content_id}}} {{embed:content_block_email_address:#{second_email_address.document.content_id}}}" })
-    end
-
-    it "should create links" do
-      expect {
-        put "/v2/content/#{content_id}", params: payload.to_json
-      }.to change(Link, :count).by(2)
-
-      expect(Link.find_by(target_content_id: first_email_address.content_id)).not_to be_nil
-      expect(Link.find_by(target_content_id: second_email_address.content_id)).not_to be_nil
-    end
-
-    it "should send transformed content to the content store" do
-      put "/v2/content/#{content_id}", params: payload.to_json
-
-      expect_content_store_to_have_received_details_including({ "body" => "#{first_email_address.details[:email_address]} #{second_email_address.details[:email_address]}" })
+      expect_content_store_to_have_received_details_including({ "body" => array_including({ "content_type" => "text/govspeak", "content" => "#{presented_details_for(first_contact)} #{presented_details_for(second_contact)}" }) })
     end
   end
 
@@ -226,7 +201,7 @@
     it "should send transformed content to the content store" do
       put "/v2/content/#{content_id}", params: payload.to_json
 
-      expect_content_store_to_have_received_details_including({ "body" => "#{email_address.details[:email_address]} #{contact.title}" })
+      expect_content_store_to_have_received_details_including({ "body" => "#{presented_details_for(email_address)} #{presented_details_for(contact)}" })
     end
   end
 
diff --git a/spec/presenters/content_embed_presenter_spec.rb b/spec/presenters/content_embed_presenter_spec.rb
index 84e2160e3..0c35765b8 100644
--- a/spec/presenters/content_embed_presenter_spec.rb
+++ b/spec/presenters/content_embed_presenter_spec.rb
@@ -16,7 +16,7 @@
   end
   let(:details) { {} }
 
-  before do
+  let!(:embedded_edition) do
     embedded_document = create(:document, content_id: embedded_content_id)
     create(
       :edition,
@@ -29,12 +29,24 @@
   end
 
   describe "#render_embedded_content" do
+    let(:expected_value) { "VALUE" }
+    let(:stub_block) { double(ContentBlockTools::ContentBlock, render: expected_value) }
+
+    before do
+      expect(ContentBlockTools::ContentBlock).to receive(:new).with(
+        document_type: embedded_edition.document_type,
+        content_id: embedded_edition.document.content_id,
+        title: embedded_edition.title,
+        details: embedded_edition.details,
+      ).at_least(:once).and_return(stub_block)
+    end
+
     context "when body is a string" do
       let(:details) { { body: "some string with a reference: {{embed:contact:#{embedded_content_id}}}" } }
 
       it "returns embedded content references with values from their editions" do
         expect(described_class.new(edition).render_embedded_content(details)).to eq({
-          body: "some string with a reference: VALUE",
+          body: "some string with a reference: #{expected_value}",
         })
       end
     end
@@ -50,8 +62,8 @@
       it "returns embedded content references with values from their editions" do
         expect(described_class.new(edition).render_embedded_content(details)).to eq({
           body: [
-            { content_type: "text/govspeak", content: "some string with a reference: VALUE" },
-            { content_type: "text/html", content: "some string with a reference: VALUE" },
+            { content_type: "text/govspeak", content: "some string with a reference: #{expected_value}" },
+            { content_type: "text/html", content: "some string with a reference: #{expected_value}" },
           ],
         })
       end
@@ -64,7 +76,7 @@
 
       it "returns embedded content references with values from their editions" do
         expect(described_class.new(edition).render_embedded_content(details)).to eq({
-          body: { title: "some string with a reference: VALUE" },
+          body: { title: "some string with a reference: #{expected_value}" },
         })
       end
     end
@@ -91,7 +103,7 @@
             parts: [
               body: [
                 {
-                  content: "some string with a reference: VALUE",
+                  content: "some string with a reference: #{expected_value}",
                   content_type: "text/govspeak",
                 },
               ],
@@ -106,7 +118,7 @@
     context "when the embedded content is available in multiple locales" do
       let(:details) { { body: "some string with a reference: {{embed:contact:#{embedded_content_id}}}" } }
 
-      before do
+      let!(:welsh_edition) do
         embedded_document = create(:document, content_id: embedded_content_id, locale: "cy")
         create(
           :edition,
@@ -121,17 +133,18 @@
       context "when the document is in the default language" do
         it "returns embedded content references with values from the same language" do
           expect(described_class.new(edition).render_embedded_content(details)).to eq({
-            body: "some string with a reference: VALUE",
+            body: "some string with a reference: #{expected_value}",
           })
         end
       end
 
       context "when the document is in an available locale" do
         let(:document) { create(:document, locale: "cy") }
+        let(:embedded_edition) { welsh_edition }
 
         it "returns embedded content references with values from the same language" do
           expect(described_class.new(edition).render_embedded_content(details)).to eq({
-            body: "some string with a reference: WELSH",
+            body: "some string with a reference: #{expected_value}",
           })
         end
       end
@@ -141,46 +154,16 @@
 
         it "returns embedded content references with values from the default language" do
           expect(described_class.new(edition).render_embedded_content(details)).to eq({
-            body: "some string with a reference: VALUE",
+            body: "some string with a reference: #{expected_value}",
           })
         end
       end
     end
 
-    context "when the document is an email address" do
-      let(:embedded_document) { create(:document) }
-      let(:links_hash) do
-        {
-          embed: [embedded_document.content_id],
-        }
-      end
-
-      before do
-        create(
-          :edition,
-          document: embedded_document,
-          state: "published",
-          content_store: "live",
-          document_type: "content_block_email_address",
-          details: {
-            email_address: "foo@example.com",
-          },
-        )
-      end
-
-      let(:details) { { body: "some string with a reference: {{embed:content_block_email_address:#{embedded_document.content_id}}}" } }
-
-      it "returns an email address" do
-        expect(described_class.new(edition).render_embedded_content(details)).to eq({
-          body: "some string with a reference: foo@example.com",
-        })
-      end
-    end
-
     context "when multiple documents are embedded in different parts of the document" do
       let(:other_embedded_content_id) { SecureRandom.uuid }
 
-      before do
+      let!(:other_embedded_edition) do
         embedded_document = create(:document, content_id: other_embedded_content_id)
         create(
           :edition,
@@ -192,6 +175,18 @@
         )
       end
 
+      let(:other_expected_value) { "VALUE2" }
+      let(:other_stub_block) { double(ContentBlockTools::ContentBlock, render: other_expected_value) }
+
+      before do
+        expect(ContentBlockTools::ContentBlock).to receive(:new).with(
+          document_type: other_embedded_edition.document_type,
+          content_id: other_embedded_edition.document.content_id,
+          title: other_embedded_edition.title,
+          details: other_embedded_edition.details,
+        ).at_least(:once).and_return(other_stub_block)
+      end
+
       let(:links_hash) do
         {
           embed: [embedded_content_id, other_embedded_content_id],
@@ -207,8 +202,8 @@
 
       it "returns embedded content references with values from their editions" do
         expect(described_class.new(edition).render_embedded_content(details)).to eq({
-          title: "title string with reference: VALUE2",
-          body: "some string with a reference: VALUE",
+          title: "title string with reference: #{other_expected_value}",
+          body: "some string with a reference: #{expected_value}",
         })
       end
     end
diff --git a/spec/presenters/details_presenter_spec.rb b/spec/presenters/details_presenter_spec.rb
index 1a4adfe3f..d687dfdf9 100644
--- a/spec/presenters/details_presenter_spec.rb
+++ b/spec/presenters/details_presenter_spec.rb
@@ -197,7 +197,7 @@
           let(:edition_details) { edition.details }
           let(:expected_details) do
             {
-              field_name => embeddable_content.title,
+              field_name => presented_details_for(embeddable_content),
             }.symbolize_keys
           end
 
@@ -219,8 +219,8 @@
           let(:expected_details) do
             {
               field_name => [
-                { content_type: "text/html", content: embeddable_content.title },
-                { content_type: "text/govspeak", content: embeddable_content.title },
+                { content_type: "text/html", content: presented_details_for(embeddable_content) },
+                { content_type: "text/govspeak", content: presented_details_for(embeddable_content) },
               ],
             }.symbolize_keys
           end
diff --git a/spec/presenters/queries/expanded_link_set_spec.rb b/spec/presenters/queries/expanded_link_set_spec.rb
index 577d5274f..acb0fb4d3 100644
--- a/spec/presenters/queries/expanded_link_set_spec.rb
+++ b/spec/presenters/queries/expanded_link_set_spec.rb
@@ -110,11 +110,11 @@
         expect(c[:details][:body]).to match([
           {
             content_type: "text/govspeak",
-            content: "Some contact",
+            content: presented_details_for(contact),
           },
           {
             content_type: "text/html",
-            content: "<p>Some contact</p>\n",
+            content: "<p>#{presented_details_for(contact)}</p>\n",
           },
         ])
       end
diff --git a/spec/services/embedded_content_finder_service_spec.rb b/spec/services/embedded_content_finder_service_spec.rb
index 8f6e4a304..2a29910f9 100644
--- a/spec/services/embedded_content_finder_service_spec.rb
+++ b/spec/services/embedded_content_finder_service_spec.rb
@@ -111,7 +111,7 @@
 
 RSpec.describe EmbeddedContentFinderService do
   describe ".fetch_linked_content_ids" do
-    EmbeddedContentFinderService::SUPPORTED_DOCUMENT_TYPES.each do |document_type|
+    ContentBlockTools::ContentBlockReference::SUPPORTED_DOCUMENT_TYPES.each do |document_type|
       include_examples "finds references", document_type
     end
 
diff --git a/spec/support/content_block_helpers.rb b/spec/support/content_block_helpers.rb
new file mode 100644
index 000000000..2c653fbaa
--- /dev/null
+++ b/spec/support/content_block_helpers.rb
@@ -0,0 +1,14 @@
+module ContentBlockHelpers
+  def presented_details_for(edition)
+    ContentBlockTools::ContentBlock.new(
+      document_type: edition.document_type,
+      content_id: edition.document.content_id,
+      title: edition.title,
+      details: edition.details,
+    ).render
+  end
+end
+
+RSpec.configure do |c|
+  c.include ContentBlockHelpers
+end