diff --git a/.github/workflows/ci_tests.yml b/.github/workflows/ci_tests.yml
index 348beba..e005487 100644
--- a/.github/workflows/ci_tests.yml
+++ b/.github/workflows/ci_tests.yml
@@ -27,7 +27,7 @@ jobs:
       - name: Setup build environment
         uses: lukka/get-cmake@latest
         with:
-          cmakeVersion: "~3.25.0"
+          cmakeVersion: "~3.28.0"
           ninjaVersion: "^1.11.1"
       - name: Setup MSVC
         if: startsWith(matrix.presets.platform, 'windows')
@@ -80,7 +80,7 @@ jobs:
       - name: Install Ninja
         uses: lukka/get-cmake@latest
         with:
-          cmakeVersion: "~3.25.0"
+          cmakeVersion: "~4.0.0"
           ninjaVersion: "^1.11.1"
       - name: Setup MSVC
         if: startsWith(matrix.platform.os, 'windows')
@@ -139,7 +139,7 @@ jobs:
       - name: Setup build environment
         uses: lukka/get-cmake@latest
         with:
-          cmakeVersion: "~3.25.0"
+          cmakeVersion: "~3.28.0"
           ninjaVersion: "^1.11.1"
       - name: Print installed softwares
         run: |
@@ -183,7 +183,7 @@ jobs:
       - name: Setup build environment
         uses: lukka/get-cmake@latest
         with:
-          cmakeVersion: "~3.25.0"
+          cmakeVersion: "~4.0.0"
           ninjaVersion: "^1.11.1"
       - name: Install Compiler
         id: install-compiler
diff --git a/.github/workflows/pre-commit.yml b/.github/workflows/pre-commit.yml
index 029fa76..f3c4332 100644
--- a/.github/workflows/pre-commit.yml
+++ b/.github/workflows/pre-commit.yml
@@ -73,4 +73,4 @@ jobs:
         with:
           tool_name: pre-commit
           level: warning
-          reviewdog_flags: "-fail-level=none"
+          reviewdog_flags: "-fail-level=error"
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0a3a79e..afdaf7d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
-cmake_minimum_required(VERSION 3.25)
+cmake_minimum_required(VERSION 3.28)
 
 project(
     beman.scope
@@ -9,6 +9,19 @@ project(
     VERSION 0.0.1
 )
 
+# gersemi: off
+
+# Modules opt in only on compilers that support g++-15 and clang-20+
+if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 20)
+    set(CMAKE_CXX_SCAN_FOR_MODULES 1)
+elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 15)
+    set(CMAKE_CXX_SCAN_FOR_MODULES 1)
+elseif()
+    set(CMAKE_CXX_SCAN_FOR_MODULES 0)
+endif()
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
 # [CMAKE.SKIP_TESTS]
 option(
     BEMAN_SCOPE_BUILD_TESTS
@@ -29,10 +42,39 @@ option(
     ${PROJECT_IS_TOP_LEVEL}
 )
 
-add_library(beman.scope INTERFACE)
+message(
+    "Compiler is: ${CMAKE_CXX_COMPILER_ID} version:  ${CMAKE_CXX_COMPILER_VERSION}"
+)
+message(
+    "cmake is: ${CMAKE_VERSION} modules scan :  ${CMAKE_CXX_SCAN_FOR_MODULES}"
+)
+
+if(CMAKE_CXX_SCAN_FOR_MODULES)
+    add_library(beman.scope)
+    target_sources(
+        beman.scope
+        PUBLIC
+            FILE_SET HEADERS
+            BASE_DIRS include
+            FILES include/beman/scope/scope.hpp
+        PUBLIC
+            FILE_SET CXX_MODULES
+            BASE_DIRS include
+            FILES include/beman/scope/beman.scope.cppm
+    )
+else()
+    add_library(beman.scope INTERFACE)
+    target_sources(
+        beman.scope
+        INTERFACE
+            FILE_SET HEADERS
+            BASE_DIRS include
+            FILES include/beman/scope/scope.hpp
+    )
+endif()
+
 add_library(beman::scope ALIAS beman.scope)
 
-# gersemi: off
 set_target_properties(
     beman.scope
     PROPERTIES
@@ -40,24 +82,21 @@ set_target_properties(
         EXPORT_NAME scope
 )
 
-target_sources(
-    beman.scope
-    INTERFACE
-        FILE_SET HEADERS
-        BASE_DIRS include
-        FILES include/beman/scope/scope.hpp
-)
+include(GNUInstallDirs)
 
 install(
     TARGETS beman.scope
-    EXPORT beman.scope-targets
     COMPONENT beman.scope
+    EXPORT beman.scope-targets
+
+    FILE_SET CXX_MODULES
+        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
     FILE_SET HEADERS
 )
+
 # gersemi: on
 
 if(BEMAN_SCOPE_INSTALL_CONFIG_FILE_PACKAGE)
-    include(GNUInstallDirs)
     include(CMakePackageConfigHelpers)
 
     write_basic_package_version_file(
@@ -77,6 +116,7 @@ if(BEMAN_SCOPE_INSTALL_CONFIG_FILE_PACKAGE)
         EXPORT beman.scope-targets
         DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/beman.scope
         NAMESPACE beman::
+        CXX_MODULES_DIRECTORY cxx-modules
         COMPONENT beman.scope
     )
 endif()
diff --git a/README.md b/README.md
index ae6c14d..55003db 100644
--- a/README.md
+++ b/README.md
@@ -85,23 +85,32 @@ Full runnable examples can be found in `examples/`.
 ## Integrate beman.scope into your project
 
 Beman.scope is a header-only library that currently relies on TS implementations
-and is thus currently available only on GCC13 and up, or Clang 19 and up -- in C++20 mode.
+and is thus currently available only on g++-13 and up, or clang 19 and up -- in C++20 mode.
+
+Note that modules support is currently tested only on clang++-19 and above and g++-15.
 
 As a header only library no building is required to use in a project -- simply make
 the `include` directory available add add the following to your source.
 
 ```cpp
 #include <beman/scope/scope.hpp>
+
+//modular version
+
+import beman.scope;
 ```
+Withmodules import needs to be after any includes to avoid compilation errors.
 
 ## Building beman.scope
 
-Building is only required to run tests and examples.
+Building is only required to run tests and examples. All compilers build and
+run `include` based tests. Compilers known to support modules are automatically
+detected added to tests.
 
 ### Build Dependencies
 
-The library itself has no build dependencies other than Catch2 for testing
-and cmake.
+The library itself has no build dependencies other than Catch2 for testing.
+And for building cmake and ninja.  Makefiles are supported in non-modular builds.
 
 Build-time dependencies:
 
@@ -110,14 +119,21 @@ Build-time dependencies:
   - CMake defaults to "Unix Makefiles" on POSIX systems
 - `catch2` for building tests
 
-### How to build beman.scope
+### How to build beman.scope tests and examples
+
+from root of repo:
 
 ```shell
-cmake --workflow --preset gcc-debug
+mkdir build; cd build;
+cmake .. -DCMAKE_CXX_COMPILER=g++-15 -DCMAKE_CXX_STANDARD=26 -G=Ninja
+ninja -j 5 -v; ctest
+```
+
+or using cmake presets
+```shell
 cmake --workflow --preset gcc-release
 cmake --install build/gcc-release --prefix /opt/beman.scope
 ```
-
 # License
 
 Source is licensed with the Apache 2.0 license with LLVM exceptions
diff --git a/examples/scope-module.cpp b/examples/scope-module.cpp
new file mode 100644
index 0000000..c5f26e8
--- /dev/null
+++ b/examples/scope-module.cpp
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// This example uses c++20 modules with beman.scope
+//
+// The following are by hand instructions for compiling with g++-15
+// first line generates gcm.cache file for standard headers - one time only
+// g++-15 -std=c++26 -O2 -fmodules -fsearch-include-path -fmodule-only -c bits/std.cc
+// g++-15 -std=c++26 -O2 -fmodules -fmodule-only -c ${scope_top}/include/beman/scope/beman.scope.cppm
+// g++-15 -std=c++26 -fmodules scope-module.cpp
+//
+// prints:
+// --> scope start
+// construct noisy
+// --> scope end
+// destroy noisy
+// scope exit: true success: true fail: false
+
+import std;
+import beman.scope;
+
+// clang-format off
+struct noisy_resource {
+    noisy_resource()  { std::print( "construct noisy\n" ); }
+    ~noisy_resource() { std::print( "destroy noisy\n"   ); }
+};
+
+int main() {
+
+    bool exit_ran, success_ran, fail_ran = false;
+    {
+        std::print("--> scope start\n");
+        beman::scope::scope_exit    _([&exit_ran]    { exit_ran = true;    });
+        beman::scope::scope_success _([&success_ran] { success_ran = true; });
+        beman::scope::scope_fail    _([&fail_ran]    { fail_ran = true;    });
+        auto                        resource_ptr = beman::scope::unique_resource(new noisy_resource(),
+                                                          // Cleanup function
+                                                          [](noisy_resource* ptr) { delete ptr; });
+        std::print("--> scope end\n");
+    } // Normal scope exit
+
+    std::print("scope exit: {} success: {} fail: {} \n", exit_ran, success_ran, fail_ran);
+}
diff --git a/include/beman/scope/beman.scope.cppm b/include/beman/scope/beman.scope.cppm
new file mode 100644
index 0000000..59ce381
--- /dev/null
+++ b/include/beman/scope/beman.scope.cppm
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+// create the beman.scope.gcm in gcm.cache directory
+// g++-15 -std=c++26 -O2 -fmodules -fmodule-only -c ${scopetop}/include/beman/scope/beman.scope.cppm
+module;
+
+#include "scope.hpp"
+
+export module beman.scope;
+
+export namespace beman::scope {
+using ::beman::scope::scope_exit;
+using ::beman::scope::scope_fail;
+using ::beman::scope::scope_success;
+using ::beman::scope::unique_resource;
+} // namespace beman::scope
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 55d7d48..1444b00 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -9,7 +9,12 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(Catch2)
 
-set(ALL_TESTNAMES scope_success scope_exit scope_fail unique_resource)
+# module tests will only compile with gcc15 or clang20 and above
+if(CMAKE_CXX_SCAN_FOR_MODULES)
+    set(ALL_TESTNAMES scope_success scope_exit scope_fail unique_resource module)
+else()
+    set(ALL_TESTNAMES scope_success scope_exit scope_fail unique_resource)
+endif()
 
 message("Tests to be built: ${ALL_TESTNAMES}")
 
diff --git a/tests/module.test.cpp b/tests/module.test.cpp
new file mode 100644
index 0000000..a4b22fc
--- /dev/null
+++ b/tests/module.test.cpp
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch_all.hpp>
+
+// for g++-15 the order is important -- import after includes
+import beman.scope;
+
+struct DummyResource {
+    bool& cleaned;
+
+    DummyResource(bool& flag) : cleaned(flag) { cleaned = false; }
+
+    bool is_clean() const { return cleaned; }
+};
+
+TEST_CASE("module-test", "[scope_module_test]") {
+    bool exit_ran, success_ran, fail_ran = false;
+    bool cleaned = true;
+    {
+        // clang-format off
+        beman::scope::scope_exit    _se([&exit_ran]    { exit_ran = true;    });
+        beman::scope::scope_success _ss([&success_ran] { success_ran = true; });
+        beman::scope::scope_fail    _sf([&fail_ran]    { fail_ran = true;    });
+        auto                        resource_ptr = beman::scope::unique_resource(new DummyResource(cleaned),
+										 [](DummyResource* ptr) { ptr->cleaned =true; delete ptr; });
+	REQUIRE(cleaned == false);
+	REQUIRE(resource_ptr->is_clean() == false);
+        //  clang-format on
+    } // Normal scope exit
+
+    REQUIRE(exit_ran == true);
+    REQUIRE(success_ran == true);
+    REQUIRE(fail_ran == false);
+    REQUIRE(cleaned == true);
+
+}