The belief-action gap was originally conceptualized by psychologists who aimed to ground behaviour in beliefs but found that their models had little predictive value. The recurrent use of this concept often comes with the assumption that human behaviour is somewhat irrational or weirdly misaligned with their beliefs. This gap is particularly striking in the environmental domain, where many people seemingly think one way but act another. In this chapter, we review a number of factors that hinder general beliefs from translating into actual behaviours. We emphasize the existence of measurement issues, information deficits about the exact impact of one’s actions, structural factors and psychological factors that together impact the robustness of the association between beliefs and actions. In particular, socio-cognitive factors have a massive impact on people’s decisions to act in ways that are aligned with their deep- seated beliefs. Once all these factors are properly taken into account, it becomes clear that the belief-action gap is not a token of human irrationality but should in fact be expected.