We examined infants' ability to generalize effective actions in an imitation task. In Experiment 1, 15-month-olds imitated effective and ineffective actions on two similarly designed toys. They were then shown a third toy of the same design with both actions available. Children reliably touched and manipulated the effective action handle first and more persistently. In Experiment 2, however, 15-month-olds did not generalize the efficacy of the action when the test toy was different from the two demonstration toys. Experiment 3 replicated the findings of Experiment 2 but also showed that infants generalized efficacy when the demonstration toys differed from one another as well as from the test toy. Our findings are consistent with a computational model that uses certain rational pedagogical assumptions. Overall, the results suggest that 15-month-olds are sensitive to the sampling information they observe and use this information to guide whether to generalize efficacy information they learn from imitation. © 2012 Elsevier Inc.