The study arranges 384 findings according to three types of influences (social, attitudinal, intrapersonal) and four levels of influence (ultimate, distal, proximal, immediate). The bulk of evidence reconfirmed the importance of several predictors of ISU (intentions and prior substance-related behavior, friendship patterns and peer behaviors, absence of supportive parents, psychological temperament), revealed that a few variables thought to be well-established predictors may not be (parental behaviors, parental permissiveness, depression, low self-esteem), and uncovered several variables where findings were either sparse or inconsistent (the role of public policies concerning ISU, mass media depictions of ISU, certain parenting styles, affective states, perceptions of parental disapproval for ISU and substance-specific refusal skills). Tables, appendix, references