Members of 26 MySpace social groups for self-injury (SI) provided data for this study investigating knowledge of SI, friends’ perceptions of SI, and the impact of online activity on SI. This study proposes that people who have belonged to these online SI groups for longer periods have higher levels of SI knowledge than those group members who have recently joined. In addition, the study proposes that individuals who self-injure have higher levels of SI knowledge than professionals who work with individuals who self-injure. An additional purpose of this study is to explore information regarding the reasons why people belong to online SI groups, the outcomes of participating in them, and their perceptions of their online peers’ and face-to-face peers’ attitudes regarding SI. A convenience sample of 101 members solicited from SI social groups on MySpace completed the survey, which consisted of five sections including the following: demographics, experiences with SI, knowledge of SI, activities related to SI in MySpace groups, and perceptions of online and face-to-face peers’ attitudes regarding SI. The knowledge section of the survey contains a 20 item measure previously used by Jeffrey and Warm (2002). A knowledge score was created based on participants responses to these 20 items. This score was used in the analysis of both hypotheses one and two. Results indicate that participants have a good understanding of SI, based on their mean knowledge score. In addition, results reveal that the current sample’s mean SI knowledge level is higher than are four of the seven groups' mean knowledge scores. Length of membership on online SI groups is not significantly greater for individuals who score higher on the knowledge of SI measure as assessed through independent t tests. Descriptive information indicates that participants perceive their online friends to react more positively to their self-injurious behaviors than they do their face-to-face friends. In addition, the sample does not indicate that participation in online SI groups has an impact on the frequency of their self-injurious behaviors, which is consistent with prior research (Murray & Fox, 2006). Limitations discussed include sample size and solicitation, survey length, and the lack of a thorough assessment of online activity.