Today, the majority of American adults uses the internet and looks for health information online. Of interest in this dissertation are people who do not subscribe to mainstream views of health, and may use the internet to discover, bolster, or share their alternative views. Although the Centers for Disease Control and Prevention (CDC) have named fluoridated drinking water and vaccination as two of the top ten public health achievements of the 20th century, there is a significant minority of people who has concerns about the safety and effectiveness of these practices. There are two essential purposes for this dissertation. First, it describes the nature of internet use among people who hold nonmainstream views of health issues. Second, it tests the hypotheses that the extent of people's internet use is a reflection of two classes of influence: 1) individual traits, such as demographic characteristics, feelings of estrangement, and need for cognition, and 2) their inability to find support from other sources, specifically mainstream media and their face-to-face social network. These analyses are informed by three sets of data: interviews with people who have varying views on fluoridation, a pair of nationally representative surveys (one on the MMR vaccine, and one on fluoridated water), and a corresponding pair of purposive surveys. The interview results identified important themes and issues surrounding nonmainstream health beliefs, especially their connection to personal experience and perceived credibility of information sources. The representative surveys found that approximately 10% of Americans believe that the MMR vaccine and fluoridated water are unsafe, with the rest of the population about evenly divided between being uncertain and believing that the health measures are safe. Notably, believing that these measures were unsafe was unrelated to any demographic characteristics, but internet use on those topics was strongly related. Internet use on those topics was associated with youth and college education, as well as perceiving the news media as having a different view from their own. The lack of social network support for one's views on these topics, however, was unrelated to internet use. The implications of these findings and future research directions are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]