Trust in government agencies plays a key role in advancing these organizations' agendas, influencing behaviors, and effectively implementing policies. However, few studies have examined the extent to which individuals are aware of and trust the leading United States agencies devoted to protecting the public's health. Using two national samples of adolescents (N = 1,125) and adults (N = 5,014), we examined demographic factors, with a focus on vulnerable groups, as correlates of awareness of and trust in the Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA), and the federal government. From nine different weighted and adjusted logistic regression models, we found high levels of awareness of the existence of the FDA and CDC (ranging from 55.7% for adolescents' awareness of the CDC to 94.3% for adults' awareness of the FDA) and moderate levels of trust (ranging from a low of 41.8% for adults' trust in the federal government and a high of 78.8% for adolescents' trust of the FDA). In the adolescent and adult samples, awareness was higher among non-Hispanic Blacks and respondents with low numeracy. With respect to trust, few consistent demographic differences emerged. Our findings provide novel insights regarding awareness and trust in the federal government and specific United States public health agencies. Our findings suggest groups to whom these agencies may want to selectively communicate to enhance trust and thus facilitate their communication and regulatory agendas.