Background: Research suggests that psychiatric conditions in children and adolescents are highly debilitating, with sparse resources for assessment and treatment in low- and middle-income countries (LMICs). Objectives: The primary aim of this study was to evaluate the reliability, validity, and latent factor structure of an ethnographically-grounded assessment instrument for detecting common mental health complaints among rural Kenyan children and adolescents. Methods: The Ndetei–Othieno–Kathuku Scale (NOK) was delivered to 2 282 children aged 10 to 18 years old. Exploratory factor analysis identified four latent factors. This structure was confirmed in subsequent confirmatory factor analyses. External validity was explored by investigating associations among NOK factors and Youth Self-Report DSM-oriented scales. Results: Findings suggest the NOK possesses good internal reliability and a four-factor latent structure corresponding to depression, anxiety, somatic complaints, and a mixed factor. Significant associations ranging from small to medium effect sizes were noted between NOK factors and YSR DSM-oriented scales. Conclusions: Exploratory findings suggest that the NOK possesses adequate psychometric properties among this population. This ethnographically-grounded instrument may be uniquely suited to screening for mental health complaints among Kenyan children and adolescents.