With privacy settings on social networking sites (SNS) perceived as complex and difficult to use and maintain, young adults can be left vulnerable to others accessing and using their personal information. Consequences of not regulating the boundaries their information on SNS include the ability for current and future employers to make career-impacting decisions based upon their online reputation that may include disqualifying them as job candidates. On SNS, such as Facebook, LinkedIn, and Twitter, young adults must decide on how to manage their online reputation by regulating boundaries to their own personal and professional information and identities. One known practice for the regulation of boundaries is the use of multiple profile management (MPM), where users of SNS create and use multiple accounts on a SNS and separate the social and professional identities that they disclose publicly and privately. The purpose of the study was to understand the lived experiences of young adults in how they regulate boundaries on SNS, through the use of MPM, as they manage their online reputation to different audiences. The practice was studied by applying interpretative phenomenological analysis (IPA) through interviewing young adults of 18-23 years of age, who use MPM on a SNS. Semi-structured interviews permitted participants to provide in-depth descriptions of their lived experiences. Eight themes were identified and described based on the analysis of the interviews that include: SNS use with online audiences, motivations for using MPM, the processes for the presentation of self, online search results, privacy settings, untagging SNS posts, self-editing and censorship, and new features. The themes describe the complexity and challenges that young adults face with regulating boundaries with their professional and social identities online through the use of MPM. Findings from this study have implications for a variety of audiences. Through the findings of this study, SNS developers can introduce new features, improve usability related to privacy management, and further encourage use of their networks. Users of SNS can use this study to understand risks of using SNS and for learning of practices for how to manage their online reputation on SNS.