English-language social and behavioral science research into US self-help/mutual aid groups and nonprofit organizations (e.g., Alcoholics Anonymous, Parents Without Partners, or bereavement groups) is reviewed. The review begins in the 1960s and proceeds into the new millennium, when institutionalized self-help/mutual aid was co-opted and renamed “support groups” by professionals. SHGs are intentionally created, single-issue, voluntary member-run mutual benefit groups that value the authority of lived experience, are cost-free, and where peers give and receive help from each other. Research attention expanded to European and Asian research in the 1990s, but has now switched to mental health peer support.