Two experiments investigated choice in adult humans on a simulated cooperation task to evaluate a risk-reduction account of sharing based on the energy-budget rule. The energy-budget rule is an optimal foraging model that predicts risk-averse choices when net energy gains exceed energy requirements (positive energy budget) and risk-prone choices when net energy gains fall below energy requirements (negative energy budget). Because sharing can minimize variability in energy gain (i.e., is a risk-averse strategy), the model predicts that sharing should occur under positive but not negative budget conditions. Energy budgets were modeled by substituting money gains for energy gains and earnings requirements for energy requirements. Participants chose between work-alone or work-with-others (sharing) response options. Experiment 1 investigated the effects on choice of manipulating the value of the earnings requirement and the presence of the partner's money counter. Choice for the sharing option varied as a function of the earnings requirement in a pattern consistent with the predictions of the energy-budget rule. The presence of the partner's money counter did not influence preference. Experiment 2 replicated Experiment 1 and also showed that under conditions with no earnings requirement (conditions in which the energy-budget rule makes no predictions), subjects often preferred the sharing option over the independent option when sharing increased the partner's earnings, and that subjects often preferred an independent option over the sharing option when the independent option produced a constant earnings amount. Overall, the results replicate and extend the results of earlier earnings-budget studies and further show that laboratory procedures are useful for evaluating the predictions of risk-sensitive and social-foraging models. (Contains 6 figures and 2 tables.)