Addressing the climate crisis requires urgent transitions in all sectors of society. Psychological research can help enable these transitions by investigating barriers and facilitators of pro-environmental behavior. Cognitive effort is a crucial factor in implementing behaviors. However, the role of cognitive effort in this context has largely been neglected, or has indirectly been assumed to be a barrier (and behavioral interventions were designed to reduce cognitive effort). Contemporary frameworks of cognitive effort have revaluated its function as a barrier, and show that effort can also add value. In four experimental studies, we capitalize on these insights and aim to test if cognitive effort can act as a facilitator of pro-environmental behavior. The first two studies will investigate the positive role of cognitive effort in an adapted version of a well-established effort paradigm in the laboratory. The last two studies will move beyond the lab and assess real-world climate action, namely, sustainable food consumption and support for climate movements. We acknowledge the societal embeddedness of research on collective climate action and will design parts of the experiments through a co-creation process together with relevant societal partners. This project will both provide fundamental insights into the cognitive psychology of effort in decision-making, and make a real-world contribution to testing ways for effective pro-environmental behavior change.