The present meta-analysis investigated the effectiveness of strategies derived from the process model of emotion regulation in modifying emotional outcomes as indexed by experiential, behavioral, and physiological measures. A systematic search of the literature identified 306 experimental comparisons of different emotion regulation (ER) strategies. ER instructions were coded according to a new taxonomy, and meta-analysis was used to evaluate the effectiveness of each strategy across studies. The findings revealed differences in effectiveness between ER processes: Attentional deployment had no effect on emotional outcomes (d+ = 0.00), response modulation had a small effect (d+ = 0.16), and cognitive change had a small-to-medium effect (d+ = 0.36). There were also important within-process differences. We identified 7 types of attentional deployment, 4 types of cognitive change, and 4 types of response modulation, and these distinctions had a substantial influence on effectiveness. Whereas distraction was an effective way to regulate emotions (d+ = 0.27), concentration was not (d+ = −0.26). Similarly, suppressing the expression of emotion proved effective (d+ = 0.32), but suppressing the experience of emotion or suppressing thoughts of the emotion-eliciting event did not (d+ = −0.04 and −0.12, respectively). Finally, reappraising the emotional response proved less effective (d+ = 0.23) than reappraising the emotional stimulus (d+ = 0.36) or using perspective taking (d+ = 0.45). The review also identified several moderators of strategy effectiveness including factors related to the (a) to-be-regulated emotion, (b) frequency of use and intended purpose of the ER strategy, (c) study design, and (d) study characteristics.