A significant number of individuals around the world live with limb absence and use prosthetic technologies to assist and enable them in various ways about their lives. The aim of this study was to enhance our understanding of prosthesis use through exploring a core concern of prosthesis users and to develop a theory of how this concern is managed. By employing classical Grounded Theory methodology (Glaser, 1978, 1992, 1998, 2001, 2003, 2005, 2009, 2011a, 2013, 2014; Glaser & Strauss, 1967), data from 24 participants that used upper- and/or lower-limb prostheses were collected and analysed. These individuals were interviewed using a flexible, unstructured interviewing style. In addition to interviews, data from internet forums, blogs and autobiographical texts were also included, all of which were analysed in accordance with the established procedures of Grounded Theory methodology, which included open and selective coding, theoretical memoing, and theoretical sampling. A main concern of being ‘just normal’ emerged through analyses, and the data were further explored in order to develop a theory of the resolving of this concern. Just normal is the condition of being and living in ways that persons variously perceive are ‘about right’; that are sufficient, that are fair, and generally how things ‘ought to be’ for them, as they see it. Three modes of just normal were identified, which were: preserving being just normal, where persons manage threats to their ability to be this way, redressing to just normal when this is judged to be lacking and so persons bring themselves into alignment with this, and persevering with just normal, accounting for how persons keep going with living just normally and despite difficulties that may accompany this. The theory provides a novel perspective on users of prostheses and elucidates the benefits and challenges of living with artificial limbs, as persons make efforts to live in ways they see as fitting with what they consider is just normal. Such an understanding has the potential to facilitate multidisciplinary teams involved in the appropriate fitting of prostheses, inform goal-setting in rehabilitation, and how to manage further consultations. The theory links to existing research and goes beyond this in providing an understanding of what compels prosthesis users to act in particular ways. It also has the transferrable potential to related areas of living with assistive technologies, the experience of disability more broadly, and beyond.