As a model of communication and engagement, citizen science has the potential to promote individual and collective climate change action. This article systematically reviewed literature that jointly addressed climate change and nature-based citizen science and identified 23 reported learning outcomes. Overall, evidence related to learning outcomes was limited across reviewed studies, but documentation of outcomes that are directly relevant to collective climate action was particularly scarce. Findings suggest more research examining citizen science from a collective climate action perspective is needed. To support future research efforts, results link the 23 revealed learning outcomes to two potential evaluation frameworks.