People living in low-income multi-problem households may benefit from participation in a community-based health promotion program. Yet, low participation rates are often a problem. It is important to assess reasons for (not) participating to better tailor programs to the needs of this particular at-risk group. Back2Balance is a health promotion program for low-income multi-problem households from Apeldoorn, the Netherlands. We performed qualitative interviews among participants (n = 16) and non-participants (n = 12) of the program and asked them for their reasons for (not) participating in the program. Interview transcripts were thematically analysed using the Framework method. Participants indicated that reasons for participating encompassed intrapersonal motivators (e.g. to become healthier), interpersonal motivators (e.g. participating to get to know new people) and program level motivators (e.g. learning about a healthy lifestyle, and free or very low cost). Participants and non-participants outlined the importance of intrapersonal barriers (e.g. physical health problems), interpersonal barriers (e.g. family circumstances) and program level barriers (e.g. logistic issues, and not understanding or knowing about some part of the program). Concluding, combining health promotion with social interaction motivated participants to participate in the Back2Balance program. Yet, both participants and non-participants experienced many barriers for participation, some of which were related to their multi-problem situation.