Objectives: Investigations of the benefits of membership of a cancer self-help group have suggested that it leads to improved sense of support, increased ability to deal with life-events, and decreased anxiety, confusion, depression and helplessness. However, some evidence suggests that people from black and ethnic groups are less likely to join a cancer self-help group. The main aims of the reported study were: to explore possible reasons why people from some ethnic groups have not participated in self-help to the same extent as the rest of the community; and to identify ways in which participation of people from ethnic groups can be increased. Methods: A qualitative interview-based study of 68 people active in self-help was carried out as a partnership between an academic institution and a community organisation. Results: A thematic analysis of the interview transcripts identified three main aspects of the value of being a member of a self-help group, regardless of interviewees' self-identified ethnicity: forming a sense of togetherness, learning from one other, and developing mutuality. We identify a number of reasons that discourage or encourage people from black and ethnic groups to join cancer self-help groups. Conclusion: We discuss some limits, identified by interviewees, that affect development of feelings of togetherness and mutuality and we conclude with some brief recommendations about widening participation in cancer self-help. Copyright (C) 2008 John Wiley & Sons, Ltd.