These risk factors included family size, birth order, socioeconomic status, family drug use, parental history of alcoholism, parental absence, and family history of incarceration. The two measures of age of emancipation were age on leaving school and age on leaving home. Age of onset of regular use was measured for the following drugs: tobacco, alcohol, marijuana, and heroin. Incarceration measures included the occurrence of juvenile detention and the time spent in prison prior to first addiction. Educational attainment was a score on a California State achievement test. Larger family size, higher birth order, parental alcoholism and parental absence were found to have a cumulatively negative effect on how young the respondents were when they first left home and when they first used particular drugs regularly, on their level of tested academic achievement, and on their probability of juvenile detention. Implications for social policies designed to prevent drug abuse are discussed. 2 tables, 80 references. (Author abstract)