Background: Cognitively stimulating activities contribute to the accumulation of cognitive reserve that is proposed to be instrumental for maintaining cognitive functioning in aging. Adopting a novel, more general conceptual perspective including models of vulnerability, we argue that cognitive reserve may modify the longitudinal association between perceived stress and the rate of subsequent decline in executive functioning. Objective: The present study set out to investigate the longitudinal relationship between perceived stress and subsequent decline in executive functioning over 6 years as measured through performance changes in the Trail Making Test (TMT) and whether this longitudinal relationship differed by key markers of cognitive reserve (education, occupation, and leisure activities), taking into account age, sex, and chronic diseases as covariates. Methods: We used latent change score modeling based on longitudinal data from 897 older adults tested on TMT parts A and B in two waves 6 years apart. Mean age in the first wave was 74.33 years. Participants reported information on perceived stress, education, occupation, leisure activities, and chronic diseases. Results: The longitudinal relationship between greater perceived stress in the first wave of data collection and steeper subsequent decline in executive functioning over 6 years was significantly reduced in individuals who had pursued a higher frequency of leisure activities in the first wave. Conclusion: The longitudinal relationship between perceived stress and subsequent decline in executive functioning may be attenuated in individuals who have accumulated greater cognitive reserve through an engaged lifestyle. Implications for current cognitive reserve and gerontological research are discussed.