This talk outlines a structural equation modeling approach to the study of reserve capacity of elderly adults in aging-sensitive fluid intelligence tasks. Latent curve analysis (LCA; Meredith & Tisak) is used to analyze longitudinal multivariable data on plasticity in fluid abilities of aged people. Subsequently, LCA is extended to the multiple-population case to disentangle training from practice effects. Statistical power associated with the model tests and with the parameter restriction tests is estimated. The empirical results suggest considerable reserve capacity of elder persons in the fluid subabilities Induction and Figural Relations.