Commitment and the hypocrisy paradigm are two models used to convince people to adopt proenvironmental behaviors. The aim of the present study is to compare the effect of those interventions with a delay between the intervention and the observation of the behavior as this has not been investigated yet. People in a Parisian supermarket were asked to commit themselves by signing a poster advocating the target behavior: no use of plastic bags (commitment condition). Some of them were also asked to remember past transgressions to arouse cognitive dissonance (hypocrisy condition). Attention was paid to whether participants took free plastic bags. Our results showed that participants in the commitment condition were more likely to change their behavior than the participants in the control condition and in the hypocrisy condition. In a final section, implications for the two models are discussed.