Active participation of community partners in research aspects of community-academic partnered projects is often assumed to have a positive impact on the outcomes of such projects. The value of community engagement in research, however, cannot be empirically determined without good measures of the level of community participation in research activities. Based on our recent evaluation of community-academic partnered projects centered around behavioral health issues, this article uses semistructured interview and survey data to outline two complementary approaches to measuring the level of community participation in research--a "three-model" approach that differentiates between the levels of community participation and a Community Engagement in Research Index (CERI) that offers a multidimensional view of community engagement in the research process. The primary goal of this article is to present and compare these approaches, discuss their strengths and limitations, summarize the lessons learned, and offer directions for future research. We find that whereas the three-model approach is a simple measure of the perception of community participation in research activities, CERI allows for a more nuanced understanding by capturing multiple aspects of such participation. Although additional research is needed to validate these measures, our study makes a significant contribution by illustrating the complexity of measuring community participation in research and the lack of reliability in simple scores offered by the three-model approach. (Contains 3 tables, 2 figures, and 3 notes.)