Kaizen (Japanese: 改善, "improvement") is a concept referring to business activities that continuously improve all functions and involve all employees from the CEO to the assembly line workers. Kaizen also applies to processes, such as purchasing and logistics, that cross organizational boundaries into the supply chain. It has been applied in healthcare, psychotherapy, life coaching, government, and banking.

By improving standardized programs and processes, kaizen aims to eliminate waste and redundancies (lean manufacturing). Kaizen was first practiced in Japanese businesses after World War II, influenced in part by American business and quality-management teachers, and most notably as part of The Toyota Way. It has since spread throughout the world and has been applied to environments outside of business and productivity.