The Internet is increasingly being used as a source of health advice and information by individuals with long term conditions (LTCs). Online forums allow people to interact with others with similar conditions, providing access to a form of social support that is based around the shared experiences of living with and managing an LTC. However, it is not clear how this support is integrated into people's lives and their use of health services. To date, research in this area has predominately focused on single conditions, and while it has been suggested that Internet forums may be particularly beneficial for those with 'contested' LTCs, this has not been adequately explored. This study aims to address this gap by exploring how individuals with contested and uncontested LTCs utilise Internet forums.This study used qualitative methods, and semi-structured interviews were conducted with 20 participants with ME/CFS and 21 participants with type 1 and 2 diabetes. These conditions were considered to provide an appropriate context in which to explore the use of the Internet and Internet forums for contested and uncontested LTCs. Participants were recruited via a number of online and offline routes, including discussion boards, email lists, newsletters, and face-to-face support groups. Interviews transcripts were analysed using thematic analysis.The results focused on three overlapping themes that were identified during the analysis; namely (1) the process of developing and maintaining trust on forums, (2) accessing support and empowerment online, and (3) forum users' presentations of self online. The use of online discussion groups was a complex and nuanced process, and was influenced by a number of individual and illness specific factors. Developing relationships with trusted forum members enabled individuals to give and receive support online, and provided a tool of empowerment. While access to peer support and the lived experiences of others were valued by interviewees, forums also allowed participants to access both experiential and scientific knowledge online, providing both lay and expert perspectives around LTCs. In addition, interviewees were seen to carefully manage how they presented themselves on forums, selecting the information that they shared about themselves in order to develop and maintain a particular online persona.By drawing on the advice, information, and support shared online, participants were empowered to position themselves as active participants in their own healthcare and to further engage with healthcare professionals. The findings indicate that forums can play a valuable role in aiding and motivating individuals in the daily management of LTCs, and highlight how this support is used to complement formal health services.