The purpose of this work is to analyze the factorial invariance of the Satisfaction With Life Scale across samples of adolescents and elderly persons. Data from 266 subjects were analyzed. Half were Spanish junior high-school students (65 girls and 68 boys) and the other half were Spanish elderly people (68 women and 65 men). Single-group analyses showed an acceptable one-factor model for both adolescent and elderly groups. Sequential multigroup analyses to test the equivalence of factor structures for adolescent and elderly groups showed that factor loadings and variances are not invariant. The scale is sensitive to age in these groups.