Concurrent and longitudinal analyses of the associations between intention to use and actual use of substances were examined for 847 adolescents from four different ethnic backgrounds. Five different substances were studied: Cigarettes, alcohol, cannabis, nonprescription medications, and hard drugs. Results showed that: (a) there were significant and consistent relationships between current level of substance use and intention of use for all ethnic groups. However, these measures of association varied considerably among ethnic groups and covered a wide range from .17 for Blacks on use of nonprescription medications to .69 for Hispanics on alcohol consumption; (b) the degree of association between intention and use, as well as ethnic differences gradually decreased over time; and (c) partialling out the effects of previous experimentation with drugs decreased the contribution of intention to predict future drug use to a nonsignificant level for Hispanics, to a moderate degree for Black and Asians, and remained a significant and meaningful contribution for Whites.