PROJECT ABSTRACT Acute coronary syndrome (ACS) is an urgent public health issue which contributes to over one million hospitalizations annually. Depression undermines optimal recovery following ACS, often at least partially through interference with health behaviors. Post-ACS patients with depression smoke more, adhere to medications less often, are less physically active, and have poorer diet than post-ACS patients without depression. This reduced adherence to recommended health behaviors, in turn, worsens cardiovascular health and increases risk of additional morbidity and mortality. Our team developed Behavioral Activation for Health and Depression (BA-HD) which is a behavioral activation-based intervention that integrates treatment for depression and multiple health behavior change post-ACS. The overarching goal of this R34 application is to pilot BA-HD across three distinct regions (Northeast, Midwest, and Southeast) in preparation for a subsequent fully powered multisite randomized controlled efficacy trial. Specifically, the research team will conduct a multisite pilot randomized controlled feasibility trial of BA-HD comparing the intervention to an Enhanced Usual Care (EUC) control group. This trial will accomplish two aims: First, we will examine study feasibility (e.g., recruitment, treatment engagement, retention) and acceptability of both study procedures and the BA-HD treatment. Second, we will examine the preliminary efficacy of BA-HD to improve (1) depressed mood and (2) cardiovascular health assessed via the American Heart Association’s Life’s Simple 7 Total Score. Findings from the proposed research are necessary to finalize study design in preparation for a subsequent fully powered trial to evaluate the efficacy of BA-HD to improve cardiovascular health and depression