This book presents a new law of human behavior founded by the author some twenty-five years ago but not proclaimed as a law until now. It has taken the past twenty-five years to accumulate evidence sufficient to "move" what was originally a tentative postulation to the status of an indisputable law- a relationship that applies across all people in all situations. This Law of Escalating Marginal Sacrifice (LEMS) states that when a person exerts more and more effort pursuing a job, task, or goal, the negative outcomes, or costs experienced by the person, as a result of the higher effort exerted, rise at an increasing rate--the rate of increase accelerating rapidly as one's effort capacity is approached. Such a relationship, between the effort exerted and the perceived costs associated with that effort, has profound implications for managing people in the workforce. Further, this relationship provides a vital framework for integrating the theory of the firm with the theory of individual behavior-a synthesis too long neglected.