Examines the relationship of 2 dimensions of the theory of social development--vulnerability and protectivity--in 2 samples, schoolchildren aged 10 to 15 (n=1,454) and addictive drug users (n=170). Finds that the most important protective factors act against substance use. Finds that among the predictors of the addicts some forms of escape from the family act against the development of drug use. (KW)