Theories in the social cognitive tradition have shown that many forms of regular physical activity (PA) are goal-directed; yet, the gap between intention and behavior is considerable, and these theories generally have limited explanation for intention-behavior discordance. Multi-process action control (M-PAC) was created as an organizing schematic to describe key constructs proposed to bridge the intention-behavior relationship across the initial adoption to ongoing sustainability of PA. In this chapter, we overview the theoretical lens behind M-PAC, suggesting that intention-behavior discordance is likely occurring from both strategic challenges in goal pursuit and automatic tendencies that determine why some people fail to follow through with PA intentions regularly. The proposed pathways for how critical reflective (affective judgments), regulatory (e.g. plans, monitoring, building a supportive social and physical environment), and eventual reflexive (habit, identity) constructs in M-PAC impact action control are highlighted. Finally, the efficacy of the M-PAC framework is reviewed with evidence collected thus far. Results from the observational studies generally support the proposed reflective, regulatory, and reflexive constructs of M-PAC as independent predictors of intention-behavior relations. Experimental application of M-PAC is preliminary but early evidence is also generally supportive that modifications to M-PAC constructs collectively and independently change PA. Overall, contemporary research on M-PAC demonstrates that its constructs may act as a bridge of the intention-behavior gap and, thus, augment traditional social cognitive approaches but sustained, higher quality research is warranted.