Ischemic heart disease is the leading cause of death in India, and there are likely more myocardial infarctions in India than in any other country in the world. We have previously reported heterogeneous care for patients with myocardial infarction in Kerala, a state in southern India, including both gaps in optimal care and inappropriate care. Based on that prior work, limitations from previous nonrandomized quality improvement studies and promising gains in process of care measures demonstrated from previous randomized trials, we and the Cardiological Society of India-Kerala chapter sought to develop, implement, and evaluate a quality improvement intervention to improve process of care measures and clinical outcomes for these patients. In this article, we report the rationale and study design for the ACS QUIK cluster-randomized stepped-wedge clinical trial (NCT02256657) in which we aim to enroll 15,750 participants with acute coronary syndromes across 63 hospitals. To date, most participants are men (76%) and have ST-segment elevation myocardial infarction (63%). The primary outcome is 30-day major adverse cardiovascular events defined as death, recurrent infarction, stroke, or major bleeding. Our secondary outcomes include health-related quality of life and individual- and household-level costs. We also describe the principal features and limitations of the stepped-wedge study design, which may be important for other investigators or sponsors considering cluster-randomized stepped-wedge trials.