Prior research indicates that boys show more interest in science, technology, engineering, and mathematics (STEM) than girls do. Given that Aha-experiences yield positive affect and increase interest, the question arises whether there are gender differences in Aha-experiences that could help explain the gender differences in interest. Derived from social role theory, we hypothesized that men report having Aha-experiences alone, whereas women report having Aha-experiences together with others. In a retrospective survey study comprising three independent samples (N = 899), we conducted chi-square analyses to explore the relationship of gender, social context (alone; not alone), domain, and situational interest. Across all participants, we found that men were more probably alone and women more probably together with others when they had an Aha-experience. More fine-grained analyses revealed that the effect was especially pronounced when the Aha-experience increased situational interest within STEM or the personal domain. The study suggests that social context played a different role in the occurrence of Aha-experiences in men and women. We discuss the implications of our findings for STEM instruction at school.