This study aimed to address two underexplored research questions regarding support for the separation between competence and affect self-perceptions due to differential relations to outcome criteria. First, it is tested whether higher relations between affect self-perceptions and effort than between competence self-perceptions and effort can also be found for elementary school students. Second, this study examines the generalizability of such differential outcome relations to the verbal domain. Students' competence and affect self-perceptions in math and verbal domains and self-reported effort at school were measured in a sample of 156 German 3rd-grade elementary school students. Confirmatory factor analyses demonstrated separate factors for competence and affect self-perceptions in both math and verbal domains. Latent regression analyses showed that affect self-perceptions were more highly related to effort than competence self-perceptions. With these findings, the present study adds further support to the commonly accepted separation between competence and affect self-perceptions by demonstrating their differential relations to effort and extending this finding to elementary school students and the verbal domain.