diff --git a/.changeset/rotten-meals-obey.md b/.changeset/rotten-meals-obey.md
new file mode 100644
index 00000000000..b0b132fe6a3
--- /dev/null
+++ b/.changeset/rotten-meals-obey.md
@@ -0,0 +1,7 @@
+---
+"@primer/react": patch
+---
+
+Adds 'display' text size to PRC theme. This size is described in our [typography documentation](https://primer.style/design/foundations/typography#headings), but was never added to our React theme.
+
+<!-- Changed components: _none_ -->
diff --git a/src/theme.ts b/src/theme.ts
index 7896b4e0b8f..0277487d499 100644
--- a/src/theme.ts
+++ b/src/theme.ts
@@ -43,7 +43,7 @@ const sizes = {
   xlarge: '1280px',
 }
 
-const fontSizes = ['12px', '14px', '16px', '20px', '24px', '32px', '40px', '48px']
+const fontSizes = ['12px', '14px', '16px', '20px', '24px', '32px', '40px', '48px', '56px']
 
 const space = ['0', '4px', '8px', '16px', '24px', '32px', '40px', '48px', '64px', '80px', '96px', '112px', '128px']