Changing alcohol and drug use patterns among women and ethnic minorities, such as the over-representation of Hispanics in alcohol-related deaths, drunk driving arrests, and treatment facilities, emphasize the importance of understanding substance use patterns in these populations. This study attempted to identify a single cause of substance abuse by considering a wide range of potential risk and protective factors. Data from a large sample of Caucasian and Hispanic teens (117 Hispanic, 560 Caucasian) were collected on 12 factors associated with substance abuse. Scores were summed into a Protective Factor Index (PFI) and a Risk Factor Index (RFI). Bivariate and multivariate correlation analyses were used to examine the relationship of the RFI and PFI with cigarette, alcohol, cannabis, cocaine, and hard drug use. Across time, the PFI predicted frequency and quantity of alcoholic beverage use for White females. The RFI predicted quantity of alcohol use for Hispanic males and White females, and frequency of liquor use for White males. These indices accounted for significant percentages of drug use variance across all groups; however, the R-squared values were highest for Hispanic males and lowest for Caucasian males. The RFI and PFI can accommodate a seemingly diverse range of hypotheses about the cause of substance use/abuse and can be helpful in identifying populations at risk who would benefit from prevention/intervention programs. (References are included, and statistical tables and charts are appended.) (TE)