Positive intercultural attitudes and civic action are increasingly important for youth around the world given the economic, social justice, and environmental challenges they face. Among U.S. youth and emerging adults, ethnic identity and self-efficacy are related to positive intercultural attitudes and may prompt civic engagement. Youth’s efficacy and civic involvement are critically important in sub-Saharan Africa, where rates of civil conflict are among the highest in the world. However, little research has been conducted with East African youth. In this paper, we discuss contextual challenges facing East African youth and the potential role of ethnic identity and self-efficacy in promoting peaceful and sustainable societies. We report qualitative results and scores on standard measures of self -efficacy, ethnic identity, and intercultural attitudes for 554 youth members of environmental clubs in Tanzania, Uganda, and the United States. Ethnic identity was associated with enhanced self-efficacy in East African, but not U.S. participants. East Africans scored higher on ethnic identity compared to U.S. youth and were more likely to reference intercultural attitudes in open-ended responses. Results provide some support for construct relevance in East Africa, however psychometric results, including internal consistency, validity, and factor structure, were mixed. Our results provide a cautionary tale about the import of measures across cultures and contexts. There is a need for international research, measurement development, and further explication of the meaning and function of ethnic identity across cultures.