diff --git a/src/plugins/identity/alias.js b/src/plugins/identity/alias.js
index 846d6ee..f383a5f 100644
--- a/src/plugins/identity/alias.js
+++ b/src/plugins/identity/alias.js
@@ -3,11 +3,15 @@
 import {type NodeAddressT} from "../../core/graph";
 import {githubOwnerPattern} from "../github/repoId";
 import {loginAddress as githubAddress} from "../github/nodes";
+import {userNodeType as githubUserType} from "../github/declaration";
 import {userAddress as discourseAddress} from "../discourse/address";
+import {userNodeType as discourseUserType} from "../discourse/declaration";
+import {identityType} from "./declaration";
 import {
   identityAddress,
   USERNAME_PATTERN as _VALID_IDENTITY_PATTERN,
 } from "./identity";
+import {NodeAddress} from "../../core/graph";
 
 /** An Alias is a string specification of an identity within another plugin.
  *
@@ -64,3 +68,29 @@ export function resolveAlias(
       throw new Error(`Unknown type for alias: ${alias}`);
   }
 }
+
+/**
+ * Attempt to convert a NodeAddressT to an Alias.
+ *
+ * If the provided node address corresponds to a known aliasing scheme, an
+ * alias will be returned. Otherwise, null is returned. Since it's possible
+ * that the node address is a valid user node address provided by a plugin that
+ * didn't update this alias registry, clients should endeavor to accomodate
+ * those addresses rather than erroring.
+ */
+export function toAlias(n: NodeAddressT): Alias | null {
+  const parts = NodeAddress.toParts(n);
+  const terminator = parts[parts.length - 1];
+  const prefixes: Map<string, NodeAddressT> = new Map([
+    ["github", githubUserType.prefix],
+    ["discourse", discourseUserType.prefix],
+    ["sourcecred", identityType.prefix],
+  ]);
+
+  for (const [prefix, nodePrefix] of prefixes.entries()) {
+    if (NodeAddress.hasPrefix(n, nodePrefix)) {
+      return `${prefix}/${terminator}`;
+    }
+  }
+  return null;
+}
diff --git a/src/plugins/identity/alias.test.js b/src/plugins/identity/alias.test.js
index 8e37604..0ec2154 100644
--- a/src/plugins/identity/alias.test.js
+++ b/src/plugins/identity/alias.test.js
@@ -1,9 +1,10 @@
 // @flow
 
-import {resolveAlias} from "./alias";
+import {resolveAlias, toAlias} from "./alias";
 import {loginAddress as githubAddress} from "../github/nodes";
 import {userAddress as discourseAddress} from "../discourse/address";
 import {identityAddress} from "./identity";
+import {NodeAddress} from "../../core/graph";
 
 describe("src/plugins/identity/alias", () => {
   describe("resolveAlias", () => {
@@ -90,4 +91,23 @@ describe("src/plugins/identity/alias", () => {
       });
     });
   });
+  describe("toAlias", () => {
+    function checkRoundTrip(alias) {
+      const addr = resolveAlias(alias, "https://example.com");
+      expect(toAlias(addr)).toEqual(alias);
+    }
+    it("works for a GitHub node address", () => {
+      checkRoundTrip("github/example");
+    });
+    it("works for a Discourse node address", () => {
+      checkRoundTrip("discourse/example");
+    });
+    it("works for a identity node address", () => {
+      checkRoundTrip("sourcecred/example");
+    });
+    it("returns null for an address without an aliasing scheme", () => {
+      const address = NodeAddress.fromParts(["sourcecred", "plugin", "foo"]);
+      expect(toAlias(address)).toEqual(null);
+    });
+  });
 });