Converging evidence suggests that the association between depressive symptoms and accelerated HF disease progression may involve multiple behavioral and pathophysiological pathways. This study proposes an innovative, prospective bio-behavioral monitoring study of 220 HF patients that is designed to address the issue of how depressive symptoms and their bio-behavioral manifestations are implicated in worsening HF disease. Using home-monitoring biotechnology, we propose to track fluctuations in HF disease severity using biweekly assessments of BNP over a 16-week period. Symptoms of depression and HF-related health behaviors also will be assessed biweekly via concurrent monitoring. This biweekly bio-behavioral monitoring will be framed by comprehensive baseline and 4-month assessments of depression, HF disease severity, and pathophysiological mechanisms that have been related to the presence of depressive symptoms and implicated in the progression of HF disease. Clinical outcomes also will be assessed over a subsequent average 3-year follow-up period. This study will create a unique data structure that will allow us to use contemporary statistical methods that will serve to elucidate causal associations between depressive symptoms, self-management health behaviors, pathophysiological processes, and HF disease progression and clinical outcomes. The study findings are expected to yield important advances in our understanding of why depressive symptoms may be particularly detrimental in the presence of HF and will help to inform the design of future clinical trials.