In 2002, the Society of Behavioral Medicine's special interest group on Multiple Health Behavior Change was formed. The group focuses on the interrelationships among health behaviors and interventions designed to promote change in more than one health behavior at a time. Growing evidence suggests the potential for multiple-behavior interventions to have a greater impact on public health than single-behavior interventions. However, there exists surprisingly little understanding of some very basic principles concerning multiple health behavior change (MHBC) research. This paper presents the rationale and need for MHBC research and interventions, briefly reviews the research base, and identifies core conceptual and methodological issues unique to this growing area. The prospects of MHBC for the health of individuals and populations are considerable.