Background: Support for self-management (SSM) is a prominent strand of health policy internationally, particularly for primary care. It is often discussed and evaluated in terms of patients' knowledge, skills and confidence, health-related behaviours, disease control or risk reduction, and service use and costs. However, these goals are limited, both as guides to professional practice and as indicators of its quality. In order to better understand what it means to support self-management well, we examined health professionals' views of success in their work with people with long-term conditions. This study formed part of a broader project to develop a conceptual account of SSM that can reflect and promote good practice. Methods: Semi-structured individual interviews (n = 26) and subsequent group discussions (n = 5 groups, 30 participants) with diverse health professionals working with people with diabetes and/or Parkinson's disease in NHS services in London, northern England or Scotland. The interviews explored examples of more and less successful work, ways of defining success, and ideas about what facilitates success in practice. Subsequent group discussions considered the practical implications of different accounts of SSM. Interviews and group discussions were audio-recorded, transcribed and analysed thematically. Results: Participants identified a wide range of interlinked aspects or elements of success relating to: health, wellbeing and quality of life; how well people (can) manage; and professional-patient relationships. They also mentioned a number of considerations that have important implications for assessing the quality of their own performance. These considerations in part reflect variations in what matters and what is realistically achievable for particular people, in particular situations and at particular times, as well as the complexity of questions of attribution. Conclusions: A nuanced assessment of the quality of support for self-management requires attention to the responsiveness of professional practice to a wide, complex range of personal and situational states, as well as actions and interactions over time. A narrow focus on particular indicators can lead to insensitive or even perverse judgements and perhaps counterproductive effects. More open, critical discussions about both success and the assessment of quality are needed to facilitate good professional practice and service improvement initiatives.