Japanese for continuous improvement, it began as postwar industrial recovery.
The Japanese word kaizen (改善) combines kai (改), meaning change or reform, and zen (善), meaning good or virtue.1 Together they mean improvement, or more precisely, continuous improvement. In everyday Japanese, the word carries no special industrial connotation. Improving anything, from a recipe to a habit, can be kaizen.
The concept took on its management meaning during Japan's postwar reconstruction. American quality experts, including W. Edwards Deming and Joseph Juran, were invited to Japan in the early 1950s to teach statistical process control to Japanese manufacturers.2
Toyota integrated the philosophy most visibly. The Toyota Production System, developed under Taiichi Ohno, built kaizen into daily factory operations: every worker was expected to identify waste and suggest improvements.3 The assembly line that Henry Ford had designed for speed, Toyota redesigned for adaptability.
Masaaki Imai brought the word into English with his 1986 book Kaizen: The Key to Japan's Competitive Success.4 Western companies adopted it as a management strategy. The word became synonymous with lean manufacturing, the elimination of waste, and the empowerment of frontline workers to improve their own processes.
In the Toyota Production System, any worker who spotted a defect could pull a cord to halt the entire line. The principle inverted Taylor's premise that workers should not be asked to think about what they were doing.5