This study examines the sociodemographic and health-related factors associated with current adult social media users in the United States. Data from the 2007 Health Information National Trends Study (HINTS) show that approximately 69% of US adults had access to the Internet in 2007. Among Internet users, 5% participated in online support groups, 7% reported blogging, and 23% used social networking sites. Multivariate analysis found that younger age was the only significant predictor of blogging and social networking site participation. Younger age, poorer subjective health, and a personal cancer experience predicted support group participation. Social media use is widespread among the US population, independent of education, race/ethnicity, or health care access. The study highlights that the growth of social media is not uniformly distributed across age groups. Health communication programs utilizing social media must consider the age of the targeted population to ensure messages reach the intended audience. While racial/ethnic and health status-related disparities exist in Internet access, these characteristics do not affect social media use among those with Internet access. This suggests that social media may be changing communication patterns throughout the United States. The study also found that social networking sites are the most widely used form of social media, followed by blogging and online support groups. Younger individuals are more likely to use social media, and less-educated individuals and racial/ethnic minorities are more likely to use social networking sites. However, these differences disappear in subsequent regression analyses, suggesting they are likely explained by age. The study concludes that social media use is influenced by age, and that health communication efforts utilizing social media will have the broadest reach and impact when targeting younger populations. The findings also suggest that social media can be used to reach traditionally underserved members of the population. The study emphasizes the importance of tracking sociodemographic trends of social media use to ensure effective health communication strategies. The results also indicate that social media can be used to reach a wider audience than traditional media, and that future research should continue to examine the impact of changing technologies on health disparities.This study examines the sociodemographic and health-related factors associated with current adult social media users in the United States. Data from the 2007 Health Information National Trends Study (HINTS) show that approximately 69% of US adults had access to the Internet in 2007. Among Internet users, 5% participated in online support groups, 7% reported blogging, and 23% used social networking sites. Multivariate analysis found that younger age was the only significant predictor of blogging and social networking site participation. Younger age, poorer subjective health, and a personal cancer experience predicted support group participation. Social media use is widespread among the US population, independent of education, race/ethnicity, or health care access. The study highlights that the growth of social media is not uniformly distributed across age groups. Health communication programs utilizing social media must consider the age of the targeted population to ensure messages reach the intended audience. While racial/ethnic and health status-related disparities exist in Internet access, these characteristics do not affect social media use among those with Internet access. This suggests that social media may be changing communication patterns throughout the United States. The study also found that social networking sites are the most widely used form of social media, followed by blogging and online support groups. Younger individuals are more likely to use social media, and less-educated individuals and racial/ethnic minorities are more likely to use social networking sites. However, these differences disappear in subsequent regression analyses, suggesting they are likely explained by age. The study concludes that social media use is influenced by age, and that health communication efforts utilizing social media will have the broadest reach and impact when targeting younger populations. The findings also suggest that social media can be used to reach traditionally underserved members of the population. The study emphasizes the importance of tracking sociodemographic trends of social media use to ensure effective health communication strategies. The results also indicate that social media can be used to reach a wider audience than traditional media, and that future research should continue to examine the impact of changing technologies on health disparities.