diff --git a/LICENSE b/LICENSE
index 6d109e0..9257c6d 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,21 +1,202 @@
-MIT License
-
-Copyright (c) 2020 Emmanuel I. Obi
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
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+      editorial revisions, annotations, elaborations, or other modifications
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+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
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+      "Contribution" shall mean any work of authorship, including
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+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
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+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
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+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright © 2025 The Radiativity Company
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
\ No newline at end of file
diff --git a/NOTICE b/NOTICE
new file mode 100644
index 0000000..8d07649
--- /dev/null
+++ b/NOTICE
@@ -0,0 +1,28 @@
+ucon — A dimensional analysis and unit algebra library
+© 2025 The Radiativity Company
+
+Licensed under the Apache License, Version 2.0.
+You may not use this project except in compliance with the License.
+A copy of the License is included in the LICENSE file or at:
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+This NOTICE file is part of the ucon distribution.
+
+ucon implements:
+  • A compositional unit algebra (UnitFactor, UnitProduct, UnitForm)
+  • A dimension algebra based on vector-space operations
+  • Expression-level scale separation for unit provenance
+  • A foundation for ConversionGraph-based unit transformations
+
+Portions of this software may incorporate or depend upon
+third-party libraries. Attribution notices for those components,
+if required, are included here or in the accompanying documentation.
+
+The Radiativity Company retains all trademark rights to the names:
+  • "ucon"
+  • "The Radiativity Company"
+  • "Project Calico"
+
+This file is for attribution purposes only and does not modify
+the terms of the Apache License, Version 2.0.
diff --git a/noxfile.py b/noxfile.py
index cd31532..8a3935c 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 import nox
 import re
 from subprocess import check_output
diff --git a/setup.py b/setup.py
index 556e52c..e9d7cc8 100644
--- a/setup.py
+++ b/setup.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 from os import environ as envvars
 from pathlib import Path
 from setuptools import find_packages, setup
@@ -9,7 +13,7 @@
     long_description=Path(__file__).absolute().parent.joinpath('README.md').read_text(),
     long_description_content_type='text/markdown',
     use_scm_version={'local_scheme': 'no-local-version'} if envvars.get('LOCAL_VERSION_SCHEME') else True,
-    license='MIT',
+    license='Apache-2.0',
     setup_requires=[
         'setuptools_scm==6.3.2'
     ],
@@ -24,7 +28,7 @@
         'Intended Audience :: Education',
         'Intended Audience :: Science/Research',
         'Topic :: Software Development :: Build Tools',
-        'License :: OSI Approved :: MIT License',
+        'License :: OSI Approved :: Apache Software License',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
diff --git a/tests/__init__.py b/tests/__init__.py
index e69de29..a54931d 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -0,0 +1,3 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
diff --git a/tests/ucon/__init__.py b/tests/ucon/__init__.py
index e69de29..a54931d 100644
--- a/tests/ucon/__init__.py
+++ b/tests/ucon/__init__.py
@@ -0,0 +1,3 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
diff --git a/tests/ucon/test_algebra.py b/tests/ucon/test_algebra.py
index 562adca..3624861 100644
--- a/tests/ucon/test_algebra.py
+++ b/tests/ucon/test_algebra.py
@@ -1,4 +1,6 @@
-
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
 
 import math
 from unittest import TestCase
diff --git a/tests/ucon/test_core.py b/tests/ucon/test_core.py
index 37819a9..6b573cf 100644
--- a/tests/ucon/test_core.py
+++ b/tests/ucon/test_core.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 import math
 import unittest
 
diff --git a/tests/ucon/test_quantity.py b/tests/ucon/test_quantity.py
index abfd44e..12112b7 100644
--- a/tests/ucon/test_quantity.py
+++ b/tests/ucon/test_quantity.py
@@ -1,4 +1,6 @@
-
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
 
 import unittest
 
diff --git a/tests/ucon/test_units.py b/tests/ucon/test_units.py
index 29ab712..9863f62 100644
--- a/tests/ucon/test_units.py
+++ b/tests/ucon/test_units.py
@@ -1,4 +1,7 @@
 
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
 
 from unittest import TestCase
 
diff --git a/ucon/__init__.py b/ucon/__init__.py
index 92c7c03..05ea68d 100644
--- a/ucon/__init__.py
+++ b/ucon/__init__.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 """
 ucon
 ====
diff --git a/ucon/algebra.py b/ucon/algebra.py
index 4b47b41..d46e4ce 100644
--- a/ucon/algebra.py
+++ b/ucon/algebra.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 """
 ucon.algebra
 ============
diff --git a/ucon/core.py b/ucon/core.py
index 1f63404..d212416 100644
--- a/ucon/core.py
+++ b/ucon/core.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 """
 ucon.core
 ==========
diff --git a/ucon/quantity.py b/ucon/quantity.py
index 22d8455..eb0ac1c 100644
--- a/ucon/quantity.py
+++ b/ucon/quantity.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 """
 ucon.quantity
 ==========
diff --git a/ucon/units.py b/ucon/units.py
index 59744a9..6c35e13 100644
--- a/ucon/units.py
+++ b/ucon/units.py
@@ -1,3 +1,7 @@
+# © 2025 The Radiativity Company
+# Licensed under the Apache License, Version 2.0
+# See the LICENSE file for details.
+
 """
 ucon.units
 ===========