diff --git a/src/main/java/com/devcycle/sdk/server/common/model/DevCycleUser.java b/src/main/java/com/devcycle/sdk/server/common/model/DevCycleUser.java
index 955417a4..24206a66 100755
--- a/src/main/java/com/devcycle/sdk/server/common/model/DevCycleUser.java
+++ b/src/main/java/com/devcycle/sdk/server/common/model/DevCycleUser.java
@@ -139,15 +139,17 @@ static void setCustomValue(Map<String, Object> customData, String key, Value val
      *
      * @param ctx A context to load a targeting key and user data from
      * @return An initialized DevCycleUser with data from the context
-     * @throws TargetingKeyMissingError if the targeting key or user_id attribute is not set
+     * @throws TargetingKeyMissingError if none of the targeting key, user_id, or userId attributes are set or valid
      */
     public static DevCycleUser fromEvaluationContext(EvaluationContext ctx) {
         String userId = "";
 
         if (ctx != null && ctx.getTargetingKey() != null && !ctx.getTargetingKey().isEmpty()) {
             userId = ctx.getTargetingKey();
-        } else if (ctx != null && ctx.getValue("user_id") != null) {
+        } else if (ctx != null && ctx.getValue("user_id") != null && ctx.getValue("user_id").isString()) {
             userId = ctx.getValue("user_id").asString();
+        } else if (ctx != null && ctx.getValue("userId") != null && ctx.getValue("userId").isString()) {
+            userId = ctx.getValue("userId").asString();
         }
 
         if (userId == null || userId.isEmpty()) {
@@ -160,7 +162,7 @@ public static DevCycleUser fromEvaluationContext(EvaluationContext ctx) {
         Map<String, Object> privateCustomData = new LinkedHashMap<>();
 
         for (String key : ctx.keySet()) {
-            if (key.equals("user_id") || key.equals("targetingKey")) {
+            if (key.equals("user_id") || key.equals("targetingKey") || key.equals("userId")) {
                 continue;
             }
 
diff --git a/src/test/java/com/devcycle/sdk/server/common/model/DevCycleUserTest.java b/src/test/java/com/devcycle/sdk/server/common/model/DevCycleUserTest.java
index 99a4d550..1aa68ee1 100644
--- a/src/test/java/com/devcycle/sdk/server/common/model/DevCycleUserTest.java
+++ b/src/test/java/com/devcycle/sdk/server/common/model/DevCycleUserTest.java
@@ -70,6 +70,113 @@ public void testCreateUserOnlyUserId() {
         Assert.assertEquals(user.getUserId(), "user-4567");
     }
 
+    @Test
+    public void testFromEvaluationContextWithUserId() {
+        Map<String, Value> apiAttrs = new LinkedHashMap();
+        apiAttrs.put("userId", new Value("test-userId-123"));
+
+        // ensure fallback to userId when target key and user_id are null
+        EvaluationContext ctx = new MutableContext(null, apiAttrs);
+        DevCycleUser user = DevCycleUser.fromEvaluationContext(ctx);
+        Assert.assertEquals(user.getUserId(), "test-userId-123");
+
+        // ensure fallback to userId when target key and user_id are empty
+        ctx = new MutableContext("", apiAttrs);
+        user = DevCycleUser.fromEvaluationContext(ctx);
+        Assert.assertEquals(user.getUserId(), "test-userId-123");
+    }
+
+    @Test
+    public void testFromEvaluationContextUserIdPriorityOrder() {
+        Map<String, Value> apiAttrs = new LinkedHashMap();
+        apiAttrs.put("user_id", new Value("user_id_value"));
+        apiAttrs.put("userId", new Value("userId_value"));
+
+        // Test priority: targetingKey > user_id > userId
+        // When all three are present, targetingKey should win
+        EvaluationContext ctx = new MutableContext("targetingKey_value", apiAttrs);
+        DevCycleUser user = DevCycleUser.fromEvaluationContext(ctx);
+        Assert.assertEquals(user.getUserId(), "targetingKey_value");
+
+        // When targetingKey is null, user_id should win over userId
+        ctx = new MutableContext(null, apiAttrs);
+        user = DevCycleUser.fromEvaluationContext(ctx);
+        Assert.assertEquals(user.getUserId(), "user_id_value");
+
+        // When targetingKey is empty, user_id should win over userId
+        ctx = new MutableContext("", apiAttrs);
+        user = DevCycleUser.fromEvaluationContext(ctx);
+        Assert.assertEquals(user.getUserId(), "user_id_value");
+
+        // When only userId is present, it should be used
+        Map<String, Value> userIdOnlyAttrs = new LinkedHashMap();
+        userIdOnlyAttrs.put("userId", new Value("userId_only_value"));
+        ctx = new MutableContext(null, userIdOnlyAttrs);
+        user = DevCycleUser.fromEvaluationContext(ctx);
+        Assert.assertEquals(user.getUserId(), "userId_only_value");
+    }
+
+    @Test
+    public void testFromEvaluationContextUserIdExcludedFromCustomData() {
+        Map<String, Value> apiAttrs = new LinkedHashMap();
+        apiAttrs.put("userId", new Value("test-userId-123"));
+        apiAttrs.put("customField", new Value("customValue"));
+
+        // When userId is used as the user ID, it should be excluded from custom data
+        EvaluationContext ctx = new MutableContext(null, apiAttrs);
+        DevCycleUser user = DevCycleUser.fromEvaluationContext(ctx);
+        
+        Assert.assertEquals(user.getUserId(), "test-userId-123");
+        Assert.assertNotNull(user.getCustomData());
+        Assert.assertEquals(user.getCustomData().size(), 1);
+        Assert.assertEquals(user.getCustomData().get("customField"), "customValue");
+        Assert.assertFalse(user.getCustomData().containsKey("userId"));
+    }
+
+    @Test
+    public void testFromEvaluationContextAllUserIdFieldsExcludedFromCustomData() {
+        Map<String, Value> apiAttrs = new LinkedHashMap();
+        apiAttrs.put("user_id", new Value("user_id_value"));
+        apiAttrs.put("userId", new Value("userId_value"));
+        apiAttrs.put("customField", new Value("customValue"));
+
+        // All user ID fields should be excluded from custom data regardless of which is used
+        EvaluationContext ctx = new MutableContext(null, apiAttrs);
+        DevCycleUser user = DevCycleUser.fromEvaluationContext(ctx);
+        
+        Assert.assertEquals(user.getUserId(), "user_id_value");
+        Assert.assertNotNull(user.getCustomData());
+        Assert.assertEquals(user.getCustomData().size(), 1);
+        Assert.assertEquals(user.getCustomData().get("customField"), "customValue");
+        Assert.assertFalse(user.getCustomData().containsKey("userId"));
+        Assert.assertFalse(user.getCustomData().containsKey("user_id"));
+        Assert.assertFalse(user.getCustomData().containsKey("targetingKey"));
+    }
+
+    @Test
+    public void testFromEvaluationContextInvalidUserIdTypes() {
+        Map<String, Value> apiAttrs = new LinkedHashMap();
+        
+        // Test with non-string userId value - should be ignored
+        apiAttrs.put("userId", new Value(123));
+        EvaluationContext ctx = new MutableContext(null, apiAttrs);
+        
+        try {
+            DevCycleUser.fromEvaluationContext(ctx);
+            Assert.fail("Expected TargetingKeyMissingError");
+        } catch (TargetingKeyMissingError e) {
+            // expected
+        }
+
+        // Test with non-string user_id value but valid userId string - should use userId
+        apiAttrs.put("user_id", new Value(456));
+        apiAttrs.put("userId", new Value("valid-userId"));
+        ctx = new MutableContext(null, apiAttrs);
+        
+        DevCycleUser user = DevCycleUser.fromEvaluationContext(ctx);
+        Assert.assertEquals(user.getUserId(), "valid-userId");
+    }
+
     @Test
     public void testCreateUserWithAttributes() {
         Map<String, Value> apiAttrs = new LinkedHashMap();