Approximately one-third of stroke survivors have symptoms of depression. A better understanding of the early risk factors implicated in this form of comorbidity may contribute to the development of early prevention strategies and to improving outcomes for this population. The current study uses ecological momentary assessment techniques to identify behavioral risk factors for depression 3 months after stroke. Thirty-six participants completed ambulatory monitoring of daily life circumstances (location, social environment, and activity) 5 times per day during a 1-week period after hospital discharge. Clinician-administered measures of depression were also provided before discharge and 3 months later. Ambulatory monitoring revealed that depression scores at 3 months were lower among individuals with more social interactions but higher among those who reported having sports activities and working in the week following hospital discharge. Daily life behaviors may have important implications for understanding the risk of poststroke depression, and mobile technologies may provide important contributions to their investigation.