diff --git a/src/RelationshipClass.ts b/src/RelationshipClass.ts
index 6f649a0..a783cc7 100644
--- a/src/RelationshipClass.ts
+++ b/src/RelationshipClass.ts
@@ -132,6 +132,14 @@ export enum RelationshipClass {
    */
   IS = 'IS',
 
+  /**
+   * A relationship indicating a Person knows another Person.
+   *
+   * Examples:
+   * Person - KNOWS -> Person
+   */
+  KNOWS = 'KNOWS',
+
   /**
    * A relationship indicating an Entity limits or restricts another Entity.
    *