Background and ObjectivesProviding appropriate and culturally sensitive care to the rapidly growing number of U.S. Latinx older adults with psychiatric conditions presents a major public health challenge. We know little about older Latinx adults’ perceived causes of mental health problems, offering clinicians limited insight to guide successful and culturally congruent treatment. Moreover, there is a paucity of mental health research examining heterogeneity in how Latinx individuals may attribute mental health symptoms. The present study sought to identify how Latinx and non-Latinx older adults attributed the sources of their mental health problems and how these types of attributions differ by ethnicity.Research Design and MethodsThis study analyzed data collected from a retrospective chart review and survey of 673 adults aged 55–95 years (430 Mexican origin and 244 non-Latinx) from a rural psychiatric outpatient clinic near the California–Mexico border. We conducted stratified latent class analysis (LCA) by race/ethnicity to explore the mental health attribution beliefs of Mexican-origin and non-Latinx clinic patients.ResultsDifferent LCA patterns for Mexican-origin Latinx versus non-Latinx groups were found. For non-Latinx adults, there was a class of individuals who attributed their mental health issues to social and financial problems. For Mexican-origin adults, there was a class of individuals who attributed their mental health issues to spiritual and/or supernatural factors, unaffected by acculturation level, depressive symptom severity, and time spent in the United States, but differing by gender. We found within-group heterogeneity: Not all Mexican-origin or non-Latinx older adults were alike in how they conceptualized their mental health.Discussion and ImplicationsMexican-origin Latinx and non-Latinx older adults attributed their mental health issues to different causes. More Mexican-origin older adults attributed their symptoms to spiritual causes, even after controlling for contextual factors. Further research is needed to determine whether attribution beliefs are affected by specific mental health diagnoses and other cultural factors not measured in this study.