Recent studies have shown that in situations where resources have been acquired collaboratively, children at around 3 years of age share mostly equally. We investigated 3-year-olds' sharing behavior with a collaborating partner and a free-riding partner who explicitly expressed her preference not to collaborate. Children shared more equally with the collaborating partner than with the free rider. These results suggest that young children are sensitive to the contributions made by others to a collaborative effort (and possibly their reasons for not collaborating) and distribute resources accordingly. (Contains 2 figures and 1 table.)