Using data on life satisfaction from the 1975 Harris National Survey, the psychometric equivalent of the factor structures was examined across four age groupings: ages 18 to 30, 31 to 44, 45 to 64, and 65 and over. Factor invariance was not supported. Results point out that the factor structures of the age groups were dissimilar and that the structure of life satisfaction differed between the age groups. The youngest group displayed a future orientation factor while for the oldest group expectations for the future were tied to other issues such as general past evaluation and getting the important things out of life. Questions are raised as to the appropriateness of comparing mean differences between age groups in light of the findings of different factor structures. (Author)