There has been a great deal of social theory written about how groups form and affect members in the offline world, but less research about how online groups can affect the behaviors and identity of the individuals who choose to participate in them. Pro-anorexia, or pro-ana, websites have been shown to have an effect on those individuals who participate in and/or view them by previous research, but previous research is inconsistent or lacking concerning the reason(s) for that effect. This study analyzes qualitative data gathered from 22 pro-ana websites over 18 months, and suggests how Collins' theory of interaction ritual chains can be extended to understand how those who participate in those websites generate emotional energy to aid them in identifying with being pro-anorexic and continue with this identity. This theory states that four initiating conditions (the ability to assemble, common linguistic and behavioral norms, and a shared focus of attention) create a boundary to outsiders, which then allows for the formation of a social group through an interaction ritual chain. This creation of an ‘in-group’ allows for the generation of emotional energy and group solidarity, which cements identity as a ‘pro-ana’ individual in an established pro-ana network. Overall, this paper argues that the extension of this theory to online social situations and the consequent understanding of the presence of this network may have implications for the understanding of how online homophilous social networks affect embedded individuals and how existing theory about social interactions can be adapted to apply to online interactions.