Memory decline is a concern for aging populations across the globe. Positive affect plays an important role in healthy aging, but its link with memory decline has remained unclear. In the present study, we examined associations between positive affect (i.e., feeling enthusiastic, attentive, proud, active) and memory (i.e., immediate and delayed recall), drawing from a 9-year longitudinal study of a national sample of 991 middle-age and older U.S. adults. Results revealed that positive affect was associated with less memory decline across 9 years when analyses controlled for age, gender, education, depression, negative affect, and extraversion. Findings generalized across another measure that assessed additional facets of positive affect, across different (but not all) facets of positive affect and memory, and across age, gender, and education; findings did not emerge for negative affect. Reverse longitudinal associations between memory and positive affect were not significant. Possible pathways linking positive affect and memory functioning are discussed. [This is the online version of an article published in "Psychological Science."]