Several reviews have concluded that exercise and/or fitness level impacts human cognition. However, much of this research has treated cognition as a unified construct rather than exploring the impact of exercise on cognition as a function of the type of cognitive task being performed or the cognitive abilities of the performer. The current work examined the effects of an acute bout of aerobic exercise in college-age adults (N = 40) on working memory capacity (WMC). WMC is at heart the ability to control, regulate, and actively maintain information with immediate relevance to the task at hand and is strongly related to several higher-level cognitive functions such as general intellectual ability, reasoning, and analytic skill. A within-subjects design was used in this study. In the Control condition, baseline WMC was assessed, and aerobic fitness was measured using a graded exercise test. In the Experimental condition, participants engaged in a 30 min run/walk on a treadmill, maintaining a target heart rate of 60-80% of age-predicted maximum. Immediately following the exercise bout, WMC was assessed. Control and Experimental condition order were counterbalanced across participants. Consistent with previous work showing exercise impacts executive functioning, WMC was found to be significantly greater in the Exercise condition than in the Control condition (ES = 0.23). This effect appears robust, in that 30 minutes of moderate-intensity exercise produced significant changes in WMC in a healthy, young-adult sample. Exercise-induced WMC changes could be attributed to improved efficiency of working memory (filtering out of irrelevant information) and/or improved maintenance of goal-oriented information. These findings suggest that relatively short bouts of exercise may be effective in enhancing working memory function. The impact of exercise on WMC as a function of individual differences in cognitive ability are also discussed.Keyword(s): disease prevention/wellness, exercise/fitness/physical activity