Scientists are increasingly called upon to engage in policy formulation, but the literature on engagement is strong on speculation and weak on evidence. Using a survey administered at several broadly “ecological” conferences, we investigated: (1) the extent to which respondents engage in policy-related activities (including reporting scientific results, interpreting science for policy makers, integrating science into decision making, taking a position on a policy issue, and acting as a decision maker); (2) what factors best explain these types of engagement; and (3) whether respondents' activity levels match their stated beliefs on such activities. Different factors explain different forms of participation. Past negative experience was identified as a barrier to taking part in policy, while self-perceived competence in navigating the science–policy interface was consistently important in explaining activity across all engagement types, highlighting the importance of training programs linking scientists to policy. Many respondents believed that scientists should interpret, integrate, and advocate, which contrasts with previous research and relatively low levels of self-reported participation in policy.