In this article we first describe a broad multilevel framework representing the determinants of human behavior and consider its advantages. Expanding on the upper part of this framework, we then propose the Multilevel Personality in Context (MPIC) model, showing how it integrates and extends past theorizing on the hierarchical organization of personality. The model builds upon McAdams's three-tier (traits, goals, and selves) conception of personality, adding a foundational level (psychological needs) beneath individual differences and incorporating social relations and cultural factors as higher level influences upon behavior and individual differences. New data (N = 3,665 in 21 cultures) are briefly presented showing that culture, self, motive, and trait variables each have independent effects upon subjective well-being (SWB) and showing that psychological need satisfaction (at the foundational level) mediates these effects as predicted. Consistent with McAdams and Pals's (2006) "fifth principle" of personality, culture had top-down effects upon self-level variables and moderated several of the relations to SWB. We conclude by suggesting some general heuristics for designing studies using the MPIC approach.