There are plenty of theories that may support the protective role of social support in the aftermath of potentially traumatic events. This meta-analytic review examined the role of received and perceived social support in promoting mental health among first responders (e.g., firefighters, police officers, and paramedics or emergency medical services personnel). Results showed that the effect sizes derived from 37 empirical studies ranged from 0 to 0.46. The overall weighted mean effect size was of medium magnitude (r=0.27). Moreover, moderator analysis showed that the effect size of perceived social support (r=0.31) was significantly higher than the effect size of received social support (r=0.22). Participants' age and gender or research design did not exert an influence on the relationship between social support and mental health. Theoretical implications and limitations are discussed. © 2010 Wiley Periodicals, Inc.