Low- and middle-income countries have a high number of orphans, many of whom have unmet mental health needs. Effective mental health interventions are needed; however, it is necessary to understand how mental health symptoms and needs are perceived locally to tailor interventions and refine measurement of intervention effects. We used an existing rapid ethnographic assessment approach to identify mental health problems from the perspective of orphans and guardians to inform a subsequent randomized controlled trial of a Western-developed, evidence-based psychosocial intervention, Trauma-focused Cognitive Behavioral Therapy. Local Kiswahili-speaking interviewers conducted 73 free list interviews and 34 key informant interviews. Results identified both common cross-cultural experiences and symptoms as well as uniquely described symptoms (e.g., lacking peace, being discriminated against) not typically targeted by the intervention or included on standardized measures of intervention effects. We discuss implications for adapting mental health interventions in low- and middle-income countries and assessing effectiveness.