Researchers have adopted many different interventions to change people’s attitudes and behaviors regarding sustainability. There has been increasingly more attention for interventions aimed at internal motivation, as opposed to interventions aimed at external motivation such as incentives. One of these interventions aimed at internal motivation is the making of commitments. The general idea of this intervention is that when people make a commitment to engage in a certain behavior, they follow up on that commitment and this produces behavior change. While this idea seems promising, the results of the studies are mixed. In the current article we review environmental studies containing a commitment manipulation, and we investigate the possible social psychological underpinnings of the commitment process. By doing so we aim to clarify how commitment can be successful and what the optimal conditions are for it to produce the desired behavior change.