This review provides a critical overview of current evidence on psychological health behavior determinants and its value in informing intervention and future determinants research. The review begins with work labeling and classifying the myriads of determinants available in the extant research to arrive at core groups of determinants. Next, the conceptual bases of these determinant groups are identified, and the weight of the evidence for their purported effects on health behavior, including belief-based determinants (e.g., outcome expectancies, capacity beliefs), determinants representing self-regulatory capacity (e.g., planning, action control) and nonconscious processes (e.g., habit, implicit cognition), and dispositional determinants (e.g., personality, regulatory control), is critically evaluated. The review also focuses on the theory-based mechanisms underpinning determinant effects and moderating conditions that magnify or diminish them. Finally, the review recommends a shift away from research on determinants as correlates, outlines how determinants can inform intervention development and mechanisms of action tests, suggests alternatives to predominant individualist approaches, and proposes future research directions.