Clayton (1992) defined risk factors as "an individual attribute, individual characteristics, situational condition, or environmental context that increases the probability of drug use or abuse or a transition in level of involvement with drugs." A protective factor "... inhibits, reduces, or buffers the probability of drug use, abuse, or a transition in the level of involvement with drugs." Although the relative power that genetic and biological factors play in the onset, continuation, and progression of alcoholism and drug abuse are not clear at this time, there is consistent evidence that family history for alcoholism is a predictor of alcoholism in subsequent generations. The genetic and biological bases of drug use, abuse, and dependence are complicated. There is clearly an interaction between the drug characteristics and the profile of the individual who is taking the drug. The search for psychological factors and individual differences that predict or cause drug use, abuse, and dependence has few organizing principles or models. One of the consistent predictors of drug-use initiation, however, is sensation seeking. Sensation seeking (Zuckerman, 1989) has been defined as "a need related to preferences for novel, complex, and ambiguous stimuli." It has been measured as a personality trait and as a part of arousability (Pandina, 1992). The family, the school, and peers are often viewed as if they had influence in drug use according to the order in which they are encountered in the developmental life cycle; however, these are not mutually exclusive domains of influence; they are often concurrent, sometimes countervailing, and always intertwined. 25 references