Activity participation provides a unique context for adolescents and emerging adults to explore interests, talents, and skills and for identity work to occur. Research has found consistent gender differences in the types of activities in which males and females participate. The current study drew on Eudaimonistic identity theory to examine the subjective identity-related experiences of personal expressiveness, flow experiences, and goal-directed behaviour [Waterman, 1984; Waterman, 2004. Finding someone to be: Studies on the role of intrinsic motivation in identity formation. Identity, 4, 209-228] within a special type of activity, self-defining activities, or those activities that participants identify as being important to who they are as a person. This study also tested for gender and country differences in a sample of 572 adolescents and emerging adults from the United States, Italy, and Chile. Findings indicate gender and country differences in the types of self-defining activities for males and females, but no gender differences in the reported identity-related experiences within those activities. This finding held across the three countries. Results from Multivariate Analyses of Variance also indicate that identity-related experiences differ significantly across seven broad activity classes. Findings are discussed in the context of the growing literature on adolescent activity involvement and time use, gender, and their relations to identity exploration.