Developing research collaborations with Indigenous communities to understand the expression and experience of anxiety and depression in American Indian (AI) youth and identifying protective and risk factors may be an important first step toward addressing AI health inequities. We used a community-based participatory research (CBPR) approach to investigate anxiety and depressive disorder symptoms among AI youth living on a Northern Plains reservation. Moreover, we examined whether symptoms were related to two potential protective and risk factors, anxiety control beliefs and rumination. Our tribal research team collected multi-reporter survey data from 71 AI 3rd-6th graders (8-13-years-old; 62.3% female) attending a tribal school, their caregivers, and teachers. Results pointed toward resilience in this sample with 7.3% and 8.7% of AI youth reporting clinical levels of anxiety and depressive disorder symptoms, respectively, and on average experiencing symptoms "Sometimes." There were moderate correlations between youth- and teacher-reported anxiety and depressive disorder symptoms, but no correlation with caregivers. Anxiety control beliefs were lower in older compared to younger AI youth and negatively related to youth-reported anxiety and depressive disorder symptoms, while rumination was positively related to youth-reported anxiety and depressive disorder symptoms and teacher-reported anxiety disorder symptoms. Age moderated relations between anxiety control beliefs and both youth-reported anxiety and depressive disorder symptoms with only significant relations found for older youth. Our findings are consistent with research showing resilience to internalizing problems in AI youth living on a reservation, but replication of their relations to anxiety control beliefs and rumination in other Indigenous peoples is warranted.