California Assembly Bill 32 (AB 32), passed in 2006, mandates reductions in California's greenhouse gas emissions to 1990 levels by 2020. Charged with implementing the bill, the California Air Resources Board has identified emission reduction strategies, including nine for agriculture. The goals set for agriculture are voluntary, but because the agricultural sector represents a significant portion of both the state's economy and its greenhouse gas emissions, it offers considerable opportunities for mitigation activities. To reduce compliance costs, the Board's plan includes a cap-and-trade program that allows for offsets to be purchased from nonregulated firms that undertake mitigation in or outside the state. However, methodologies are needed to assess the impact of mitigating activities. Without them, emission reductions are expected to fall far short of potential. We review an existing international mechanism — the Kyoto Protocol's Clean Development Mechanism (CDM) — that offers a framework for evaluating offset projects and advanced methodologies that could facilitate AB 32 implementation in California.