The present article provides an update of the author's evolving theory of the "multicultural personality" (MP). The MP is conceptualized as a narrow matrix of personality traits or dispositions (characteristic adaptations) that can be subsumed under broad trait models of personality (e.g., Big Five). MP theory posits that its constituent factors will demonstrate incremental validity over broad personality traits in predicting adaptive human behavior in increasingly culturally heterogeneous societies. The present theory of the MP is anchored across the disciplines of evolutionary biology, human ecology, personality and developmental psychology, and counseling and positive psychology. The specific definition of the MP is based on an integration of leading theories and constructs in multicultural psychology. Limitations of MP theory are highlighted, future directions for research presented, and tentative implications for counseling training and practice noted. (Contains 2 tables and 3 figures.)