Aim The aim was to explore the process of involving mental healthcare service users in a mental health promotion research project as research advisors and to articulate features of the collaboration which encouraged and empowered the advisors to make significant contributions to the research process and outcome.Background There is an increasing interest in evaluating aspects of service user involvement in nursing research. Few descriptions exist of features that enable meaningful service user involvement. We draw on experiences from conducting research which used the methodology interpretative phenomenological analysis to explore how persons with mental disorders perceived mental health. Apart from the participants in the project, five research advisors with service user experience were involved in the entire research process.Design We applied a case study design to explore the ongoing processes of service user involvement. Methods Documents and texts produced while conducting the project (2012-2016), as well as transcripts from multistage focus group discussions with the research advisors, were analysed.Results The level of involvement was dynamic and varied throughout the different stages of the research process. Six features: leadership, meeting structure, role clarification, being members of a team, a focus on possibilities and being seen and treated as holistic individuals, were guiding principles for a salutogenic service user involvement. These features strengthened the advisors' perception of themselves as valuable and competent contributors. Conclusion Significant contributions from research advisors were promoted by facilitating the process of involvement. A supporting structure and atmosphere were consistent with a salutogenic service user involvement.