diff --git a/tools/spectral/ipa/__tests__/eachEnumValueMustBeUpperSnakeCase.test.js b/tools/spectral/ipa/__tests__/eachEnumValueMustBeUpperSnakeCase.test.js
new file mode 100644
index 0000000000..14854718a2
--- /dev/null
+++ b/tools/spectral/ipa/__tests__/eachEnumValueMustBeUpperSnakeCase.test.js
@@ -0,0 +1,151 @@
+import testRule from './__helpers__/testRule';
+import { DiagnosticSeverity } from '@stoplight/types';
+
+testRule('xgen-IPA-123-enum-values-must-be-upper-snake-case', [
+  {
+    name: 'valid schema - components.schemas',
+    document: {
+      components: {
+        schemas: {
+          SchemaName: {
+            properties: {
+              exampleProperty: {
+                enum: ['EXAMPLE_A', 'EXAMPLE_B'],
+                type: 'string',
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'invalid schema with exception - components.schemas',
+    document: {
+      components: {
+        schemas: {
+          SchemaName: {
+            'x-xgen-IPA-exception': {
+              'xgen-IPA-123-enum-values-must-be-upper-snake-case': 'reason',
+            },
+            properties: {
+              exampleProperty: {
+                enum: ['exampleA', 'exampleB'],
+                type: 'string',
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'invalid schema - components.schemas',
+    document: {
+      components: {
+        schemas: {
+          SchemaName: {
+            properties: {
+              exampleProperty: {
+                enum: ['exampleA', 'exampleB'],
+                type: 'string',
+              },
+            },
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-123-enum-values-must-be-upper-snake-case',
+        message: 'exampleA enum value must be UPPER_SNAKE_CASE.  http://go/ipa/123',
+        path: ['components', 'schemas', 'SchemaName', 'properties', 'exampleProperty', 'enum', '0'],
+        severity: DiagnosticSeverity.Warning,
+      },
+      {
+        code: 'xgen-IPA-123-enum-values-must-be-upper-snake-case',
+        message: 'exampleB enum value must be UPPER_SNAKE_CASE.  http://go/ipa/123',
+        path: ['components', 'schemas', 'SchemaName', 'properties', 'exampleProperty', 'enum', '1'],
+        severity: DiagnosticSeverity.Warning,
+      },
+    ],
+  },
+  {
+    name: 'valid schema - paths.*',
+    document: {
+      paths: {
+        '/a/{exampleId}': {
+          get: {
+            parameters: [
+              {
+                schema: {
+                  type: 'string',
+                  enum: ['EXAMPLE_A', 'EXAMPLE_B'],
+                },
+              },
+            ],
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'invalid schema with exception - paths.*',
+    document: {
+      paths: {
+        '/a/{exampleId}': {
+          get: {
+            parameters: [
+              {
+                schema: {
+                  'x-xgen-IPA-exception': {
+                    'xgen-IPA-123-enum-values-must-be-upper-snake-case': 'reason',
+                  },
+                  type: 'string',
+                  enum: ['exampleA', 'exampleB'],
+                },
+              },
+            ],
+          },
+        },
+      },
+    },
+    errors: [],
+  },
+  {
+    name: 'invalid schema - paths.*',
+    document: {
+      paths: {
+        '/a/{exampleId}': {
+          get: {
+            parameters: [
+              {
+                schema: {
+                  type: 'string',
+                  enum: ['exampleA', 'exampleB'],
+                },
+              },
+            ],
+          },
+        },
+      },
+    },
+    errors: [
+      {
+        code: 'xgen-IPA-123-enum-values-must-be-upper-snake-case',
+        message: 'exampleA enum value must be UPPER_SNAKE_CASE.  http://go/ipa/123',
+        path: ['paths', '/a/{exampleId}', 'get', 'parameters', '0', 'schema', 'enum', '0'],
+        severity: DiagnosticSeverity.Warning,
+      },
+      {
+        code: 'xgen-IPA-123-enum-values-must-be-upper-snake-case',
+        message: 'exampleB enum value must be UPPER_SNAKE_CASE.  http://go/ipa/123',
+        path: ['paths', '/a/{exampleId}', 'get', 'parameters', '0', 'schema', 'enum', '1'],
+        severity: DiagnosticSeverity.Warning,
+      },
+    ],
+  },
+]);
diff --git a/tools/spectral/ipa/ipa-spectral.yaml b/tools/spectral/ipa/ipa-spectral.yaml
index 789367fc96..204b0e2db0 100644
--- a/tools/spectral/ipa/ipa-spectral.yaml
+++ b/tools/spectral/ipa/ipa-spectral.yaml
@@ -3,3 +3,4 @@ extends:
   - ./rulesets/IPA-102.yaml
   - ./rulesets/IPA-104.yaml
   - ./rulesets/IPA-109.yaml
+  - ./rulesets/IPA-123.yaml
diff --git a/tools/spectral/ipa/rulesets/IPA-123.yaml b/tools/spectral/ipa/rulesets/IPA-123.yaml
new file mode 100644
index 0000000000..23b9c66223
--- /dev/null
+++ b/tools/spectral/ipa/rulesets/IPA-123.yaml
@@ -0,0 +1,14 @@
+# IPA-123: Enums
+# http://go/ipa/123
+
+functions:
+  - eachEnumValueMustBeUpperSnakeCase
+
+rules:
+  xgen-IPA-123-enum-values-must-be-upper-snake-case:
+    description: 'Enum values must be UPPER_SNAKE_CASE. http://go/ipa/123'
+    message: '{{error}} http://go/ipa/123'
+    severity: warn
+    given: '$..enum'
+    then:
+      function: 'eachEnumValueMustBeUpperSnakeCase'
diff --git a/tools/spectral/ipa/rulesets/functions/eachEnumValueMustBeUpperSnakeCase.js b/tools/spectral/ipa/rulesets/functions/eachEnumValueMustBeUpperSnakeCase.js
new file mode 100644
index 0000000000..1850a44ca2
--- /dev/null
+++ b/tools/spectral/ipa/rulesets/functions/eachEnumValueMustBeUpperSnakeCase.js
@@ -0,0 +1,29 @@
+import { hasException } from './utils/exceptions.js';
+import { getSchemaPath, resolveObject } from './utils/componentUtils.js';
+import { casing } from '@stoplight/spectral-functions';
+
+const RULE_NAME = 'xgen-IPA-123-enum-values-must-be-upper-snake-case';
+const ERROR_MESSAGE = 'enum value must be UPPER_SNAKE_CASE.';
+
+export default (input, _, { path, documentInventory }) => {
+  const oas = documentInventory.resolved;
+  const schemaPath = getSchemaPath(path);
+  const schemaObject = resolveObject(oas, schemaPath);
+  if (hasException(schemaObject, RULE_NAME)) {
+    return;
+  }
+
+  const errors = [];
+  input.forEach((enumValue, index) => {
+    const isUpperSnakeCase = casing(enumValue, { type: 'macro' });
+
+    if (isUpperSnakeCase) {
+      errors.push({
+        path: [...path, index],
+        message: `${enumValue} ${ERROR_MESSAGE} `,
+      });
+    }
+  });
+
+  return errors;
+};
diff --git a/tools/spectral/ipa/rulesets/functions/eachPathAlternatesBetweenResourceNameAndPathParam.js b/tools/spectral/ipa/rulesets/functions/eachPathAlternatesBetweenResourceNameAndPathParam.js
index 234cb2c5a4..eb418aae61 100644
--- a/tools/spectral/ipa/rulesets/functions/eachPathAlternatesBetweenResourceNameAndPathParam.js
+++ b/tools/spectral/ipa/rulesets/functions/eachPathAlternatesBetweenResourceNameAndPathParam.js
@@ -1,4 +1,4 @@
-import { isPathParam } from './utils/pathUtils.js';
+import { isPathParam } from './utils/componentUtils.js';
 import { hasException } from './utils/exceptions.js';
 
 const RULE_NAME = 'xgen-IPA-102-path-alternate-resource-name-path-param';
diff --git a/tools/spectral/ipa/rulesets/functions/utils/componentUtils.js b/tools/spectral/ipa/rulesets/functions/utils/componentUtils.js
new file mode 100644
index 0000000000..2eb2f86d9e
--- /dev/null
+++ b/tools/spectral/ipa/rulesets/functions/utils/componentUtils.js
@@ -0,0 +1,75 @@
+/**
+ * Checks if a string belongs to a path parameter or a path parameter with a custom method.
+ *
+ * A path parameter has the format: `{paramName}`
+ * A path parameter with a custom method has the format: `{paramName}:customMethod`
+ *
+ * @param {string} str - A string extracted from a path split by slashes.
+ * @returns {boolean} True if the string matches the expected formats, false otherwise.
+ */
+export function isPathParam(str) {
+  const pathParamRegEx = new RegExp(`^{[a-z][a-zA-Z0-9]*}$`);
+  const pathParamWithCustomMethodRegEx = new RegExp(`^{[a-z][a-zA-Z0-9]*}:[a-z][a-zA-Z0-9]*$`);
+  return pathParamRegEx.test(str) || pathParamWithCustomMethodRegEx.test(str);
+}
+
+/**
+ * Extracts the schema path from the given JSONPath array.
+ *
+ * This function is designed to handle two types of paths commonly encountered in OpenAPI definitions:
+ *
+ * 1. **Component Schema Paths**:
+ *    - Represented as: `components.schemas.schemaName.*.enum`
+ *    - This path indicates that the enum is defined within a schema under `components.schemas`.
+ *    - The function returns the first three elements (`["components", "schemas", "schemaName"]`).
+ *
+ * 2. **Parameter Schema Paths**:
+ *    - Represented as: `paths.*.method.parameters[*].schema.enum`
+ *    - This path indicates that the enum is part of a parameter's schema in an operation.
+ *    - The function identifies the location of `schema` in the path and returns everything up to (and including) it.
+ *
+ * @param {string[]} path - An array representing the JSONPath structure of the OpenAPI definition.
+ * @returns {string[]} The truncated path pointing to the schema object.
+ */
+export function getSchemaPath(path) {
+  if (path.includes('components')) {
+    return path.slice(0, 3);
+  } else if (path.includes('paths')) {
+    const index = path.findIndex((item) => item === 'schema');
+    return path.slice(0, index + 1);
+  }
+}
+
+/**
+ * Resolves the value of a nested property within an OpenAPI structure using a given path.
+ *
+ * This function traverses an OpenAPI object based on a specified path (array of keys)
+ * and retrieves the value at the end of the path. If any key in the path is not found,
+ * or the value is undefined at any point, the function will return `undefined`.
+ *
+ * @param {Object} oas - The entire OpenAPI Specification object.
+ * @param {string[]} objectPath - An array of strings representing the path to the desired value.
+ *                                For example, `['components', 'schemas', 'MySchema', 'properties']`.
+ * @returns {*} The value at the specified path within the OpenAPI object, or `undefined` if the path is invalid.
+ *
+ * @example
+ * const oas = {
+ *   components: {
+ *     schemas: {
+ *       MySchema: {
+ *         properties: {
+ *           fieldName: { type: 'string' }
+ *         }
+ *       }
+ *     }
+ *   }
+ * };
+ *
+ * const result = resolveObject(oas, ['components', 'schemas', 'MySchema', 'properties']);
+ * console.log(result); // Output: { fieldName: { type: 'string' } }
+ */
+export function resolveObject(oas, objectPath) {
+  return objectPath.reduce((current, key) => {
+    return current && current[key] ? current[key] : undefined;
+  }, oas);
+}
diff --git a/tools/spectral/ipa/rulesets/functions/utils/pathUtils.js b/tools/spectral/ipa/rulesets/functions/utils/pathUtils.js
deleted file mode 100644
index 34d1910175..0000000000
--- a/tools/spectral/ipa/rulesets/functions/utils/pathUtils.js
+++ /dev/null
@@ -1,14 +0,0 @@
-/**
- * Checks if a string belongs to a path parameter or a path parameter with a custom method.
- *
- * A path parameter has the format: `{paramName}`
- * A path parameter with a custom method has the format: `{paramName}:customMethod`
- *
- * @param {string} str - A string extracted from a path split by slashes.
- * @returns {boolean} True if the string matches the expected formats, false otherwise.
- */
-export function isPathParam(str) {
-  const pathParamRegEx = new RegExp(`^{[a-z][a-zA-Z0-9]*}$`);
-  const pathParamWithCustomMethodRegEx = new RegExp(`^{[a-z][a-zA-Z0-9]*}:[a-z][a-zA-Z0-9]*$`);
-  return pathParamRegEx.test(str) || pathParamWithCustomMethodRegEx.test(str);
-}