Objective: The purpose of this meta-analysis was to examine the effect of acute aerobic exercise on self-reported positive-activated affect (PAA). Samples from 158 studies from 1979 to 2005 were included yielding 450 independent effect sizes (ESs) and a sample size of 13,101. Method: Studies were coded for moderators related to assessment time, exercise variables such as intensity, duration, and dose (combination of intensity and duration), and design characteristics. The analysis considered multiple measures of affect and corrected for statistical artifacts using Hunter and Schmidt [(1990). Methods of meta-analysis: Correcting error and bias in research findings. Newbury Park: Sage; (2004). Methods of meta-analysis: Correcting error and bias in research findings (2nd ed.). Thousand Oaks: Sage] meta-analytic methods. Results: The overall estimated mean corrected ES (over(d, -)corr) and standard deviation (SDcorr) were .47 and .37, respectively. Effects were consistently positive (a) immediately post-exercise, (b) when pre-exercise PAA was lower than average, (c) for low intensity exercise <15-39% oxygen uptake reserve (%VO2R), (d) for durations up to 35 min, and (e) for low to moderate exercise doses. The effects of aerobic exercise on PAA appear to last for at least 30 min after exercise before returning to baseline. Dose results suggest the presence of distinct zones of affective change that more accurately reflect post-exercise PAA responses than intensity or duration alone. Control conditions were associated with reductions in PAA (over(d, -)corr = - . 17, SDcorr=.25). Conclusion: The typical acute bout of aerobic exercise produces increases in self-reported PAA, whereas the typical control condition produces decreases. However, large SDcorr values suggest that additional variables, possibly related to individual differences, further moderate the effects of exercise on PAA.