Standardized assessment tools developed in western contexts may systematically miss certain problems that are considered important in non-western cultures. In this mixed-methods study, we used an open-ended assessment tool (the Top Problem Assessment; TPA) to identify culturally relevant concerns among low-income Kenyan youth. We then a) applied thematic analysis to identify the most frequently reported problems and b) examined the extent to which these problems were reflected in standardized mental health measures. Using the TPA, we identified common social, academic, and economic problems facing Kenyan youths. Specifically, 61% of the sample reported a social problem, 38% an academic problem, and 35% an economic problem. By contrast, the standardized assessments revealed that worrying and difficulty concentrating were the most commonly reported symptoms. However, the emotional and behavioral problems assessed via the standardized measures were only reported as top problems by 17% of the sample. Overall, our findings are consistent with the idea that standardized measures can miss certain culturally-salient concerns that can be acquired through open-ended assessments. We discuss how brief open-ended assessment tools could complement standardized measures, inform the development of culturally relevant standardized measures, and offer rich data about the experiences of people in understudied cultural contexts.