Behavioral hypotheses have recently been introduced into public-choice theory (Ostrom in American Political Science Review 92:1–22, 1998). Nevertheless, the individual intrinsic preferences which drive decisions in social dilemmas have not yet been empirically identified. This paper asks whether risk and inequity preferences are behind agents’ behavior in a sequential public good game. The experimental results show that risk aversion is negatively correlated with the contribution decision of first movers. Second movers who are averse to advantageous inequity free-ride less and reciprocate more than do others. Our results emphasize the importance of strategic uncertainty for the correct understanding of which preferences influence cooperation in social dilemmas.