Infants become increasingly helpful during the second year. We investigated experimentally whether adults' explicit scaffolding influences this development. Infants (N = 69, 13-18 months old) participated in a series of simple helping tasks. Half of infants received explicit scaffolding (encouragement and praise), whereas the other half did not. Among younger infants (below 15 months), infants who received explicit scaffolding helped twice as often as infants in the control group, and also helped more on several subsequent trials when no scaffolding was provided. As predicted, older infants were not affected by explicit scaffolding. These results demonstrate the influence of social experiences in early helping, but also how the effects of scaffolding may depend on the developmental level of the child. Less explicit forms of scaffolding may be effective when children are older.