This study focuses on possible differences in protective factors of substance use in early and middle adolescence. These possible differences are analysed by means of the same structural equation model applied to two different samples of adolescents: the first sample is made up of 450 adolescents, ages 12 to 14 years, and second of 203 adolescents, ages 15 to 17 years. The results indicate that adequate family communication is a protective factor in both samples, whereas high social self-esteem

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... is proposed as a risk factor in middle adolescence. The adolescent's family self-esteem and attitudes towards authority are also relevant factors in both samples. These results may have important implications in the development of future intervention programmes.