Political interest is a crucial precursor to political engagement, but little is known about how to stimulate greater interest. The article explores the role social motives have in generating interest. A laboratory experiment is used in which it is possible to manipulate beliefs about the social rewards of political engagement as well as external efficacy beliefs. Across two types of measures for political interest (self-reports and revealed preferences), connecting political engagement with social rewards led to substantial increases in political interest. Moreover, these effects were particularly strong among individuals with low levels of external efficacy. Ultimately, the data provide clear evidence that political interest can be positively stimulated with social rewards mobilisation techniques and that it is rooted in beliefs about the potential motives pursuable through politics. The paper concludes with a discussion of the broader implications of these results for studies of political participation and mobilisation efforts.