While there is reason to support marine conservation for its intrinsic value, the primary purpose of MPAs is to increase socioeconomic value to California residents (and to a lesser extent, visitors from outside the state). However, to date, there have been few serious efforts to measure the socioeconomic contributions of MPAs to the California economy. This situation needs to be addressed as many stakeholders are rightfully interested in understanding exactly what socioeconomic benefits MPAs provide for the state, as well as the distributional consequences, as there are often winners and losers in any major conservation effort. This paper presents a framework for assessing the socioeconomic contributions of MPAs, based on the demonstrable changes to natural systems that can be attributed to the protections afforded under the MPA system. First, statistical techniques are discussed that will help identify causal links between MPAs and changes in ocean conditions, using the “difference-in-difference” technique. This is followed by an overview of how these ecosystem changes can influence a wide range of human values, both “market” and “non-market”. To date, little attention has been paid to non-market values, even though this is where most of the socioeconomic benefits of MPAs are derived, particularly through recreational values, wildlife viewing, and existence values. The objective of this paper is make sure that the California policymaking community has a clear idea of how the comprehensive socioeconomic benefits of MPAs can be assessed, including the limitations, challenges, and data requirements.