Social media comprise a dynamic and rapidly expanding resource in today's information environment. This study proposes the construct of social media efficacy, or a person's perceived ability to reach desired outcomes in the social media environment, and suggests that a person's level of social media efficacy can impact how he or she evaluates information found online. Results of this survey of adult Internet users in the United States indicate that users with higher social media efficacy, who are younger and more skilled at producing and consuming social media content, tend find information shared via social media to be more trustworthy and credible than those lower in social media efficacy. These efficacious social media users also rely more both on the opinions of others and on social media specifically when evaluating or verifying the information they find online, suggesting that they may be more prone to seek out and be influenced by input from others. Overall, findings from this study indicate that people exhibit different behavior and information evaluation tendencies depending on their level of social media efficacy, suggesting the future utility of social media efficacy in exploring variance in human behavior and attitudes about information online.