Between one and two thirds of depressive disorders go undetected in primary care settings. Four hundred ninety-six Mexican American primary care patients from high-poverty areas were screened for depressive symptoms, and 41% endorsed depressive symptoms. Eighty percent of screened patients with depressive symptoms agreed to structured diagnostic interviews and 90% of those interviewed met diagnostic criteria for one or more depressive disorders. Cases of depression detected through this systematic process were compared with evidence of depression detected by providers in medical charts. Provider and study evaluation agreement was poor (kappa= 0.13); providers noted depression in 21% of patients with depressive disorders based on the systematic evaluation. More work is needed to enhance detection of depression in primary care, especially in minority populations.