The hypothesis that psychometric ability tests retain equivalent factor structures across a 7-year interval was examined in a sample of 984 persons (disaggregated into 6 cohort groups: M ages at first test = 32, 46, 53, 60, 67, and 76), assessed in 1984 and 1991 as part of the Seattle Longitudinal Study. A best fitting measurement model was estimated for 20 psychometric tests marking the 6 primary abilities of Inductive Reasoning, Spatial Orientation, Perceptual Speed, Numeric Facility, Verbal Ability, and Verbal Recall. Gender was partialed out at the variable level by including a gender factor. Weak factorial invariance over time was demonstrated for all cohorts. Configural invariance could be demonstrated across all cohort groups. However, weak factorial invariance across groups could be accepted for all but the youngest and oldest groups. Latent means were modeled for the accepted solutions across time and cohort groups.