Patients with diabetes mellitus (DM) are at increased risk for major depressive disorder (MDD), which is reliably associated with poor DM outcomes. Compared to Caucasians, African Americans are more likely to develop DM and to have poor DM outcomes. They are also more likely to have untreated MDD, and to hold beliefs about the nature and care of MDD that are not well-accommodated by current mental health care delivery systems. Despite these clear disparities, there is a dire shortage of data to guide the development of culturally-appropriate interventions for MDD comorbidity in DM, because African Americans have been tremendously under-represented in research on this topic. The significance of this empirical gap is highlighted by our preliminary data, which suggest that depressive symptoms may be more disruptive to DM control for African Americans than for Caucasians, even after adjusting for potential confounders. Specific Aim 1 is to test our conceptual model, in which the association between MDD and DM outcomes (glycemic control and DM quality of life) is both moderated by race and mediated by DM self-care behavior. We plan to study 262 Detroit-region Type 2 DM patients (50% African American, 50% Caucasian) in a 10-week assessment protocol. At Weeks 1 and 10; assessments will be made of MDD presence and severity, DM self-care, glycemic control, and DM quality of life; with an additional assessment of self-care and MDD made at mid-study. Data on self-care and MDD will be aggregated across time, and the study hypotheses will be tested using OLS multiple regression path analysis. Specific Aim 2 is to gain an understanding of depression-related behavior and beliefs that will inform the development of culturally-sensitive interventions for DM patients who have comorbid MDD. To meet Aim 2, we will develop a race-stratified subsample of 30 subjects with comorbid MDD. Using a semi-structured interview tool based on the Commonsense Model of Illness Representations, we will collect qualitative data on beliefs about the nature and care of MDD. We will perform qualitative analysis to identify and compare themes by race. Finally, we will integrate our quantitative (Aim 1) and qualitative results using triangulation and other mixed-methods approaches, to characterize cultural differences in MDD representations, treatment-seeking, and mental health barriers among DM patients. The project outcomes will advance the science of illness self-management. Findings will also enable the design of trials to develop and test innovations that improve mental and physical health for many thousands of African Americans. [unreadable] [unreadable]