Findings from several studies reveal that later born cohorts tend on average to perform better on most measurements of fluid cognitive abilities in later life as compared with earlier born cohorts measured at the same age (i.e. Flynn effects). This study investigate cohort differences in level of cognitive functioning and rate of decline in a representative sample drawn from the Gerontological and Geriatric Population Studies in Gothenburg (H70) including three birth cohorts born 1901/02, 1906/07 and 1930, and measured on tests of logical reasoning (Figure Logic) and spatial ability (Block Design), at ages 70, 75 and 79. Estimates from multiple-group latent growth curve models revealed, in accordance with previous studies, substantial cohort differences in level of performance were later born cohorts outperform earlier born. However, and somewhat surprisingly, later born cohorts also showed, on average, a steeper decline over the study period as compared with earlier born. Neither gender nor educational differences could account for the observed cohort trends. Potential explanations for these findings are further discussed in the context of neuropathology and cognitive reserve.