This document provides an overview of operational research in public health. It defines operational research as scientific study aimed at improving decision-making and program performance. The key aspects are identifying problems, generating evidence-based solutions, and implementing more effective approaches. Operational research uses both primary data collection and secondary data analysis to help modulate inputs/processes and measure outputs/outcomes/impact of health programs. It helps solve problems, inform policies, and improve quality. Examples provided include studies on domiciliary TB care and neonatal mortality reduction programs.