Application of control theory to predict human behavior is largely based on Powers’s (1973) work, which can be traced indirectly through Carver and Scheier’s (1982) self-regulation theory and directly through interventions in areas of child development, mental health, education, and organizational psychology. Control theory proposes that behavior changes from moment to moment to keep perceived aspects of the self and world close to desired reference values – a person’s goals, standards, or ideals. Control is achieved through actions that help the individual meet their standards. Individuals can change their behavior to either cooperate or conflict with their attempts to control the same perceived aspect of the world (e.g., money, food, alcohol, drugs, medicine). Control theory is a “building blocks” theory from which working models can be built and tested and sets a new standard for empirical testing of psychological theory. This chapter reviews the evidence for each component of control theory. It describes how behavior change emerges for many different reasons, each of which can be modeled and tested. The chapter also questions whether “behavior change” itself is an appropriate, or efficient, objective. Finally, the chapter summarizes evidence for behavior change interventions informed by control theory and provides suggestions for future research and interventions using the theory.