The Gilbreths’ time and motion studies, as well as their consideration of the human factors operating in the workplace, contributed to many aspects of modern management theory, including Activity-Based Costing (ABC).

Frank Bunker Gilbreth, Sr. was an early advocate of scientific management and a pioneer of motion study, and is perhaps best known as the father and central figure of the book and movie Cheaper by the Dozen. He and his wife Lillian Moller Gilbreth (the first true industrial/organizational psychologist and one of the first working female engineers holding a Ph.D) were themselves industrial engineers and efficiency experts who contributed to the study of industrial engineering in fields such as motion study as well as human factors. Their belief in the power of observation was legendary. Lillian published Psychology in the Workplace serially during the period 1912-1913.

The books Cheaper by the Dozen and Belles on Their Toes (written by their children Ernestine and Frank Jr.) tell the story of their family life and describe how they applied their interest in time and motion study to the organization and daily activities of such a large family. They founded their own management consulting firm in 1922 (Gilbreth, Inc).

Lillian continued to work and conduct seminars long after Frank had died. She is often referred to as the “first lady of management.”