Behavior change interventions based on self-determination theory focus on promoting autonomous motivation, using autonomy support to do so. This chapter outlines the autonomy-supportive intervention program (ASIP), which helps supervisors “upgrade” the quality of their motivating style toward those they supervise, as occurs in the classroom, workplace, home, sport arenas, and health care settings. This is an important approach to behavior change because, when supervisors become more autonomy-supportive and less controlling, those they supervise tend to increase their adaptive behaviors (e.g., learning, prosocial behavior) and well-being as well as to decrease their maladaptive behaviors (e.g., disengagement, antisocial behavior) and ill-being. This chapter defines the key constructs and practices featured in the ASIP (i.e., supervisor’s motivating styles, supervisee’s psychological needs); identifies the theoretical basis and the specific mechanisms by which this intervention enables behavior change; provides an overview of what occurs during an ASIP; outlines the evidence base supporting the efficacy and benefits of the intervention; and offers step-by-step guidelines for how practitioners might carry out an ASIP in different contexts and populations.