diff --git a/cel_expr_python/BUILD b/cel_expr_python/BUILD
index d4b206a..aca5cc3 100644
--- a/cel_expr_python/BUILD
+++ b/cel_expr_python/BUILD
@@ -105,14 +105,25 @@ pybind_extension(
 # For pybind11-based CEL extensions.
 pybind_library(
     name = "cel_extension",
-    hdrs = ["cel_extension.h"],
+    srcs = [
+        "py_error_status.cc",
+    ],
+    hdrs = [
+        "cel_extension.h",
+        "py_error_status.h",
+    ],
     visibility = ["//visibility:public"],
     deps = [
+        ":status_macros",
+        "@com_google_absl//absl/base:no_destructor",
+        "@com_google_absl//absl/container:flat_hash_map",
+        "@com_google_absl//absl/log:absl_check",
+        "@com_google_absl//absl/log:absl_log",
         "@com_google_absl//absl/status",
+        "@com_google_absl//absl/status:statusor",
         "@com_google_cel_cpp//compiler",
         "@com_google_cel_cpp//runtime:runtime_builder",
         "@com_google_cel_cpp//runtime:runtime_options",
-        "@com_google_protobuf//:protobuf",
     ],
 )
 
@@ -141,7 +152,10 @@ py_test(
     srcs = ["cel_env_test.py"],
     deps = [
         ":cel",
+        "//cel_expr_python/ext:ext_bindings",
         "//cel_expr_python/ext:ext_math",
+        "//cel_expr_python/ext:ext_optional",
+        "//cel_expr_python/ext:ext_strings",
         "//testing:proto2_test_all_types_py_pb2",
         "@com_google_absl_py//absl/testing:absltest",
     ],
diff --git a/cel_expr_python/cel_env_test.py b/cel_expr_python/cel_env_test.py
index 2aa16c2..79a9700 100644
--- a/cel_expr_python/cel_env_test.py
+++ b/cel_expr_python/cel_env_test.py
@@ -22,7 +22,10 @@
 
 from absl.testing import absltest
 from cel_expr_python import cel
+from cel_expr_python.ext import ext_bindings
 from cel_expr_python.ext import ext_math
+from cel_expr_python.ext import ext_optional
+from cel_expr_python.ext import ext_strings
 from cel.expr.conformance.proto2 import test_all_types_pb2 as test_all_types_pb
 
 
@@ -95,9 +98,7 @@ def test_invalid_yaml(self):
     )
 
   def test_config_export_container(self):
-    env = cel.NewEnv(
-        container="test.container"
-    )
+    env = cel.NewEnv(container="test.container")
     yaml = env.config().to_yaml()
     self.assertEqual(
         normalize_yaml(yaml),
@@ -251,6 +252,52 @@ def test_config_variable_types(self):
     self.assertEqual(res.type(), cel.Type.INT)
     self.assertEqual(res.value(), 42)
 
+  def test_config_export_extension_version(self):
+    env = cel.NewEnv(
+        extensions=[
+            ext_math.ExtMath(0),
+            ext_optional.ExtOptional(1),
+            ext_strings.ExtStrings(2),
+            ext_bindings.ExtBindings(),
+        ],
+    )
+    yaml = env.config().to_yaml()
+    self.assertEqual(
+        normalize_yaml(yaml),
+        normalize_yaml("""
+          extensions:
+            - name: "bindings"
+            - name: "math"
+              version: 0
+            - name: "optional"
+              version: 1
+            - name: "strings"
+              version: 2
+        """),
+    )
+
+  def test_config_extension_version_out_of_range(self):
+    cases = [
+        [
+            lambda: ext_math.ExtMath(42),
+            r"'math' extension version: 42 not in range \[0, \d+\]",
+        ],
+        [
+            lambda: ext_optional.ExtOptional(6),
+            r"'optional' extension version: 6 not in range \[0, \d+\]",
+        ],
+        [
+            lambda: ext_strings.ExtStrings(18),
+            r"'strings' extension version: 18 not in range \[0, \d+\]",
+        ],
+    ]
+    for test_case in cases:
+      with self.assertRaises(Exception) as e:
+        cel.NewEnv(
+            extensions=[test_case[0]()],
+        )
+      self.assertRegex(str(e.exception), test_case[1])
+
   def test_config_extensions(self):
     config = cel.NewEnvConfigFromYaml("""
       extensions:
@@ -276,14 +323,28 @@ def test_config_extensions(self):
     res = env.compile("hello('World')").eval()
     self.assertEqual(res.value(), "Hello, World!")
 
-  def test_config_extensions_override(self):
-    # TODO(b/498655870): add assertion based on extension aliases once
-    # supported.
+  def test_config_extension_override_same_version(self):
     config = cel.NewEnvConfigFromYaml("""
       extensions:
         - name: cel.lib.ext.math
+          version: 1
+        - name: strings
+          version: 2
+      """)
+    env = cel.NewEnv(
+        config=config,
+        extensions=[ext_math.ExtMath(1), ext_strings.ExtStrings(2)],
+    )
+    res = env.compile("'%.3f'.format([math.floor(3.14)])").eval()
+    self.assertEqual(res.value(), "3.000")
+
+  def test_config_extension_override_different_version(self):
+    config = cel.NewEnvConfigFromYaml("""
+      extensions:
+        - name: math
           version: 0
         - name: cel.lib.ext.strings
+          version: 2
       """)
     with self.assertRaises(Exception) as e:
       cel.NewEnv(
@@ -291,8 +352,18 @@ def test_config_extensions_override(self):
           extensions=[ext_math.ExtMath()],
       )
     self.assertIn(
-        "Extension 'cel.lib.ext.math' version 0 is already included. Cannot"
-        " also include version 'latest'",
+        "Extension 'math' version 0 is already included. Cannot"
+        " also include version 2",
+        str(e.exception),
+    )
+    with self.assertRaises(Exception) as e:
+      cel.NewEnv(
+          config=config,
+          extensions=[ext_strings.ExtStrings(1)],
+      )
+    self.assertIn(
+        "Extension 'cel.lib.ext.strings' version 2 is already included. Cannot"
+        " also include version 1",
         str(e.exception),
     )
 
diff --git a/cel_expr_python/cel_extension.h b/cel_expr_python/cel_extension.h
index 86bac22..48a7151 100644
--- a/cel_expr_python/cel_extension.h
+++ b/cel_expr_python/cel_extension.h
@@ -38,7 +38,9 @@ namespace cel_python {
 // Python.
 class CelExtension {
  public:
-  explicit CelExtension(std::string name) : name_(std::move(name)) {};
+  explicit CelExtension(std::string name, std::string alias = "",
+                        int version = -1)
+      : name_(std::move(name)), alias_(std::move(alias)), version_(version) {}
   virtual ~CelExtension() = default;
 
   virtual cel::CompilerLibrary GetCompilerLibrary() {
@@ -51,9 +53,13 @@ class CelExtension {
   }
 
   std::string name() const { return name_; }
+  std::string alias() const { return alias_; }
+  int version() const { return version_; }
 
  private:
   std::string name_;
+  std::string alias_;
+  int version_;
 };
 
 #define CEL_MODULE_NAME "cel_expr_python.cel"
@@ -80,6 +86,13 @@ class CelExtension {
         .def(pybind11::init<>());                                          \
   }
 
+#define CEL_VERSIONED_EXTENSION_MODULE(module_name, class_name)            \
+  PYBIND11_MODULE(module_name, m) {                                        \
+    pybind11::module_::import(CEL_MODULE_NAME);                            \
+    pybind11::class_<class_name, cel_python::CelExtension>(m, #class_name) \
+        .def(pybind11::init<>())                                           \
+        .def(pybind11::init<int>(), pybind11::arg("version"));             \
+  }
 }  // namespace cel_python
 
 #endif  // THIRD_PARTY_CEL_PYTHON_CEL_EXTENSION_H_
diff --git a/cel_expr_python/ext/BUILD b/cel_expr_python/ext/BUILD
index 7e32348..cdb038e 100644
--- a/cel_expr_python/ext/BUILD
+++ b/cel_expr_python/ext/BUILD
@@ -49,6 +49,7 @@ pybind_extension(
     deps = [
         "//cel_expr_python:cel_extension",
         "@com_google_absl//absl/status",
+        "@com_google_absl//absl/strings",
         "@com_google_cel_cpp//compiler",
         "@com_google_cel_cpp//extensions:math_ext",
         "@com_google_cel_cpp//extensions:math_ext_decls",
@@ -69,6 +70,8 @@ pybind_extension(
     deps = [
         "//cel_expr_python:cel_extension",
         "@com_google_absl//absl/status",
+        "@com_google_absl//absl/strings",
+        "@com_google_cel_cpp//checker:optional",
         "@com_google_cel_cpp//compiler",
         "@com_google_cel_cpp//compiler:optional",
         "@com_google_cel_cpp//runtime:optional_types",
@@ -94,9 +97,9 @@ pybind_extension(
 )
 
 pybind_extension(
-    name = "ext_string",
+    name = "ext_strings",
     srcs = [
-        "ext_string.cc",
+        "ext_strings.cc",
     ],
     data = [
         "//cel_expr_python:cel",
@@ -105,6 +108,7 @@ pybind_extension(
     deps = [
         "//cel_expr_python:cel_extension",
         "@com_google_absl//absl/status",
+        "@com_google_absl//absl/strings",
         "@com_google_cel_cpp//compiler",
         "@com_google_cel_cpp//extensions:strings",
         "@com_google_cel_cpp//runtime:runtime_builder",
diff --git a/cel_expr_python/ext/ext_bindings.cc b/cel_expr_python/ext/ext_bindings.cc
index 08caebc..49d9731 100644
--- a/cel_expr_python/ext/ext_bindings.cc
+++ b/cel_expr_python/ext/ext_bindings.cc
@@ -20,7 +20,8 @@ namespace cel_python {
 
 class ExtBindings : public CelExtension {
  public:
-  explicit ExtBindings() : CelExtension("cel.lib.ext.cel.bindings") {}
+  explicit ExtBindings()
+      : CelExtension("cel.lib.ext.cel.bindings", "bindings") {}
 
   cel::CompilerLibrary GetCompilerLibrary() override {
     return cel::extensions::BindingsCompilerLibrary();
diff --git a/cel_expr_python/ext/ext_encoders.cc b/cel_expr_python/ext/ext_encoders.cc
index cc9e2ab..59c67ae 100644
--- a/cel_expr_python/ext/ext_encoders.cc
+++ b/cel_expr_python/ext/ext_encoders.cc
@@ -23,7 +23,7 @@ namespace cel_python {
 
 class ExtEncoders : public CelExtension {
  public:
-  explicit ExtEncoders() : CelExtension("cel.lib.ext.encoders") {}
+  explicit ExtEncoders() : CelExtension("cel.lib.ext.encoders", "encoders") {}
 
   cel::CompilerLibrary GetCompilerLibrary() override {
     return cel::extensions::EncodersCompilerLibrary();
diff --git a/cel_expr_python/ext/ext_math.cc b/cel_expr_python/ext/ext_math.cc
index bb50581..4ed18ec 100644
--- a/cel_expr_python/ext/ext_math.cc
+++ b/cel_expr_python/ext/ext_math.cc
@@ -13,30 +13,41 @@
 // limitations under the License.
 
 #include "absl/status/status.h"
+#include "absl/strings/str_cat.h"
 #include "compiler/compiler.h"
 #include "extensions/math_ext.h"
 #include "extensions/math_ext_decls.h"
 #include "runtime/runtime_builder.h"
 #include "runtime/runtime_options.h"
 #include "cel_expr_python/cel_extension.h"
+#include "cel_expr_python/py_error_status.h"
 
 namespace cel_python {
 
 class ExtMath : public CelExtension {
  public:
-  explicit ExtMath() : CelExtension("cel.lib.ext.math") {}
+  explicit ExtMath(int version)
+      : CelExtension("cel.lib.ext.math", "math", version) {
+    if (version < 0 || version > cel::extensions::kMathExtensionLatestVersion) {
+      throw StatusToException(absl::InvalidArgumentError(absl::StrCat(
+          "'math' extension version: ", version, " not in range [0, ",
+          cel::extensions::kMathExtensionLatestVersion, "]")));
+    }
+  }
+
+  ExtMath() : ExtMath(cel::extensions::kMathExtensionLatestVersion) {}
 
   cel::CompilerLibrary GetCompilerLibrary() override {
-    return cel::extensions::MathCompilerLibrary();
+    return cel::extensions::MathCompilerLibrary(version());
   }
 
   absl::Status ConfigureRuntime(cel::RuntimeBuilder& runtime_builder,
                                 const cel::RuntimeOptions& opts) override {
     return cel::extensions::RegisterMathExtensionFunctions(
-        runtime_builder.function_registry(), opts);
+        runtime_builder.function_registry(), opts, version());
   }
 };
 
-CEL_EXTENSION_MODULE(ext_math, ExtMath);
+CEL_VERSIONED_EXTENSION_MODULE(ext_math, ExtMath);
 
 }  // namespace cel_python
diff --git a/cel_expr_python/ext/ext_optional.cc b/cel_expr_python/ext/ext_optional.cc
index f18f057..a54242d 100644
--- a/cel_expr_python/ext/ext_optional.cc
+++ b/cel_expr_python/ext/ext_optional.cc
@@ -13,21 +13,32 @@
 // limitations under the License.
 
 #include "absl/status/status.h"
+#include "absl/strings/str_cat.h"
+#include "checker/optional.h"
 #include "compiler/compiler.h"
 #include "compiler/optional.h"
 #include "runtime/optional_types.h"
 #include "runtime/runtime_builder.h"
 #include "runtime/runtime_options.h"
 #include "cel_expr_python/cel_extension.h"
+#include "cel_expr_python/py_error_status.h"
 
 namespace cel_python {
 
 class ExtOptional : public CelExtension {
  public:
-  explicit ExtOptional() : CelExtension("optional") {}
+  explicit ExtOptional(int version) : CelExtension("optional", "", version) {
+    if (version < 0 || version > cel::kOptionalExtensionLatestVersion) {
+      throw StatusToException(absl::InvalidArgumentError(absl::StrCat(
+          "'optional' extension version: ", version, " not in range [0, ",
+          cel::kOptionalExtensionLatestVersion, "]")));
+    }
+  }
+
+  ExtOptional() : ExtOptional(cel::kOptionalExtensionLatestVersion) {}
 
   cel::CompilerLibrary GetCompilerLibrary() override {
-    return cel::OptionalCompilerLibrary();
+    return cel::OptionalCompilerLibrary(version());
   }
 
   absl::Status ConfigureRuntime(cel::RuntimeBuilder& runtime_builder,
@@ -40,6 +51,6 @@ class ExtOptional : public CelExtension {
   }
 };
 
-CEL_EXTENSION_MODULE(ext_optional, ExtOptional);
+CEL_VERSIONED_EXTENSION_MODULE(ext_optional, ExtOptional);
 
 }  // namespace cel_python
diff --git a/cel_expr_python/ext/ext_string.cc b/cel_expr_python/ext/ext_strings.cc
similarity index 56%
rename from cel_expr_python/ext/ext_string.cc
rename to cel_expr_python/ext/ext_strings.cc
index fbda450..d1e6456 100644
--- a/cel_expr_python/ext/ext_string.cc
+++ b/cel_expr_python/ext/ext_strings.cc
@@ -13,29 +13,42 @@
 // limitations under the License.
 
 #include "absl/status/status.h"
+#include "absl/strings/str_cat.h"
 #include "compiler/compiler.h"
 #include "extensions/strings.h"
 #include "runtime/runtime_builder.h"
 #include "runtime/runtime_options.h"
 #include "cel_expr_python/cel_extension.h"
+#include "cel_expr_python/py_error_status.h"
 
 namespace cel_python {
 
-class ExtString : public CelExtension {
+class ExtStrings : public CelExtension {
  public:
-  explicit ExtString() : CelExtension("cel.lib.ext.string") {}
+  explicit ExtStrings(int version)
+      : CelExtension("cel.lib.ext.strings", "strings", version) {
+    if (version < 0 ||
+        version > cel::extensions::kStringsExtensionLatestVersion) {
+      throw StatusToException(absl::InvalidArgumentError(absl::StrCat(
+          "'strings' extension version: ", version, " not in range [0, ",
+          cel::extensions::kStringsExtensionLatestVersion, "]")));
+    }
+  }
+
+  ExtStrings() : ExtStrings(cel::extensions::kStringsExtensionLatestVersion) {}
 
   cel::CompilerLibrary GetCompilerLibrary() override {
-    return cel::extensions::StringsCompilerLibrary();
+    return cel::extensions::StringsCompilerLibrary(version());
   }
 
   absl::Status ConfigureRuntime(cel::RuntimeBuilder& runtime_builder,
                                 const cel::RuntimeOptions& opts) override {
     return cel::extensions::RegisterStringsFunctions(
-        runtime_builder.function_registry(), opts);
+        runtime_builder.function_registry(), opts,
+        cel::extensions::StringsExtensionOptions{.version = version()});
   }
 };
 
-CEL_EXTENSION_MODULE(ext_string, ExtString);
+CEL_VERSIONED_EXTENSION_MODULE(ext_strings, ExtStrings);
 
 }  // namespace cel_python
diff --git a/cel_expr_python/py_cel_env_internal.cc b/cel_expr_python/py_cel_env_internal.cc
index 7af9af2..64a1697 100644
--- a/cel_expr_python/py_cel_env_internal.cc
+++ b/cel_expr_python/py_cel_env_internal.cc
@@ -108,8 +108,29 @@ PyCelEnvInternal::NewCelEnvInternal(
     CelExtensionHandle handle(ext);
     CEL_PYTHON_ASSIGN_OR_RETURN(CelExtension * extension,
                                 handle.GetExtension());
-    // TODO(b/498655870): support extension version.
-    CEL_PYTHON_RETURN_IF_ERROR(config.AddExtensionConfig(extension->name()));
+
+    std::string name;
+    if (!extension->alias().empty() &&
+        extension->alias() != extension->name()) {
+      // If the configuration lists the extension by name, use the name;
+      // otherwise, use the alias. This allows us to detect conflicting
+      // extension registrations, whether they are included by the extension
+      // name or alias.
+      name = extension->alias();
+      for (const cel::Config::ExtensionConfig& extension_config :
+           config.GetExtensionConfigs()) {
+        if (extension_config.name == extension->name()) {
+          name = extension_config.name;
+          break;
+        }
+      }
+    } else {
+      name = extension->name();
+    }
+    CEL_PYTHON_RETURN_IF_ERROR(config.AddExtensionConfig(
+        name, extension->version() >= 0
+                  ? extension->version()
+                  : cel::Config::ExtensionConfig::kLatest));
     extension_handles.push_back(std::move(handle));
   }
 
diff --git a/conformance/BUILD b/conformance/BUILD
index 3101953..bed1210 100644
--- a/conformance/BUILD
+++ b/conformance/BUILD
@@ -45,7 +45,7 @@ py_test(
         "//cel_expr_python/ext:ext_math",
         "//cel_expr_python/ext:ext_optional",
         "//cel_expr_python/ext:ext_proto",
-        "//cel_expr_python/ext:ext_string",
+        "//cel_expr_python/ext:ext_strings",
         "@com_google_absl_py//absl/testing:absltest",
         "//testing:proto2_test_all_types_py_pb2",
         "//testing:proto3_test_all_types_py_pb2",
diff --git a/conformance/conformance_test.py b/conformance/conformance_test.py
index 58a82b9..10329c6 100644
--- a/conformance/conformance_test.py
+++ b/conformance/conformance_test.py
@@ -33,7 +33,7 @@
 from cel_expr_python.ext import ext_math
 from cel_expr_python.ext import ext_optional
 from cel_expr_python.ext import ext_proto
-from cel_expr_python.ext import ext_string
+from cel_expr_python.ext import ext_strings
 from cel.expr.conformance.proto2 import test_all_types_extensions_pb2 as test_all_types_extensions_proto2  # pylint: disable=unused-import
 from cel.expr.conformance.proto2 import test_all_types_pb2 as test_all_types_proto2  # pylint: disable=unused-import
 from cel.expr.conformance.proto3 import test_all_types_pb2 as test_all_types_proto3  # pylint: disable=unused-import
@@ -138,7 +138,7 @@ class ConformanceTest(absltest.TestCase):
       "math_ext": [ext_math.ExtMath()],
       "optionals": [ext_optional.ExtOptional()],
       "proto2_ext": [ext_proto.ExtProto()],
-      "string_ext": [ext_string.ExtString()],
+      "string_ext": [ext_strings.ExtStrings()],
       "type_deduction": [ext_optional.ExtOptional()],
   }