This mixed-methods study analyzed adolescents' evaluation of the trustworthiness of different kinds of evidence and their reasons for why they trusted (or did not trust) them. Specifically, we analyzed adolescents' rankings of seven kinds of evidence in the abstract and in the context of a settled historical event (school desegregation) and whether differences existed between their rankings. We explored the reasons adolescents provided for trusting or not trusting sources and whether differences existed between these reasons in the abstract and in context. We also explored whether rankings differed across sociocultural identities. We found that, on average, adolescents' rankings, as well as their reasoning, differed when the evidence was presented in the abstract versus in the context of school desegregation. We also found that emotion and personal relationship with the topic are compelling factors in determining students' trust in sources--a finding that has previously been overlooked in the scholarship. This study provides implications for K-12 social studies education, teacher education, and civic identity and citizenship studies.