We evaluate the direct and indirect effects of an environmental educational program with value-laded content on children's and parents' knowledge, attitudes and practices regarding the consumption and disposal of plastics.We do this using a randomized field experiment targeting fourth-grade children in Chile.The educational program had a sizeable and a positive impact on children’ knowledge, attitudes, and practices, but no effect on parents' behavior.Heterogeneous effects indicate that the program had a larger effect among children in more vulnerable schools, but there was still no effect on parents.Finally, because parents may ultimately determine what constitutes acceptable behavior for children, promoting permanent changes in behavior will require interventions of this sort to be complemented with other initiatives targeting parents. •Changing people's attitudes is an important first step in addressing environmental issues.•This paper evaluates the effects of an environmental education campaign.•We find a sizeable effect on children's knowledge, attitudes, and practices.•However, we do not find any evidence of a spillover effect on the parents' behavior.•Then, interventions targeting children should be reinforced in various ways to achieve long-term impacts.