The United States has not ratified the Kyoto Protocol, restricting the ability of forests from participating internationally as greenhouse gas (GHG) emission offset projects. As a result, a proliferation of different registry and program rules is occurring in the United States, providing an opportunity for the US forestry community to mitigate GHG emissions. This article addresses the Kyoto Protocol principles of additionality, permanence, and leakage, and challenges the way that these principles are being used to qualify forest offset projects as climate change mitigation measures. Policy initiatives are proposed for challenging policymakers and the forestry community to rethink sustainably managed forest offset project rules as the United States considers GHG emission reduction legislation.