Teenagers and young adults born between 1981 and 2000 are a critical demographic group economically and are one of the first demographics presented with an array of Internet social networking services just as their online habits are forming. Based on a survey of 34,514 teen and young adult respondents, the research reported in this paper is a descriptive and inferential analysis of reported ecommerce information behaviors on four social networking sites (Facebook, MySpace, myYearbook, and Twitter). We use k-means clustering analysis to find groups of these users based on their levels of being networked on and being engaged with social networking services. Results show that the majority of this demographic have accounts on multiple social networking sites and specific sites result in different information behaviors. More than 40% engage in three social networking sites and an additional 20% have four social networking accounts. We also found that there are distinct information behavioral differences among eight distinct clusters of users, indicating that companies may need to employ advanced analytical techniques to segment the youth market. We also investigate the motivations for using different social media sites. Findings show that this young demographic has complex ecommerce information behaviors that call for nuanced approaches in advertising, marketing, or other areas of information targeting.