A classification scheme is presented composed of 26 helping behaviours which were empirically generated and reliably coded by a team of three judges, based on a content analysis of interview protocols. The protocols describe the types of informal social support provided to a sample of single mothers. The categories are organized into four main classes of influence and each category has been defined and illustrated with an example taken from the protocols. In order to illustrate one application of the scheme, data are presented contrasting the helping behaviours extended to the women in response to three problem areas. Methods of further validating the scheme and evaluating the efficacy of informal social support are discussed. One of the hallmarks of the mental health ideology is that coping resources should be available to people experiencing stress at an early time and in their natural environment. Translated into practice, this ideology has taken the form of mental health consultation with a variety of community such as teachers, clergymen, and family physicians who have broad contact with the public and who have been trained to engage in basic diagnostic, counselling, and behaviour change activities with the clients they normally serve. Recently, however, this approach to the secondary prevention of mental disorder has been criticized both on the basis of insufficient empirical evidence of preventive outcomes (Mannino & Shore, 1975) and on grounds of professional colonialism towards the caregiver-consultees (Gottlieb, 1974). The latter criticism - that training in the professional mould may supplant or weaken the natural helping skills of caregivers - has been strengthened with the appearance of a literature documenting the existence of numerous natural forms of service delivery which operate largely outside the professional sphere of influence, but which involve a great many people (Collins & Pancoast, 1976; Gottlieb, 1976). These natural support systems range from the more organized self-help group to the spontaneous helping transactions extended within personal networks. A number of these natural human services are currently being subjected to evaluative research; however, the more general claim This research was supported by Grant No. S74-0726 from the Canada Council. Thanks are expressed to John Hughes, Barbara Piggins, Bill Psihogios, and Michael Wuitchik for their patience and attention to the minutiae associated with the development of the classification scheme. Requests for reprints should be addressed to Benjamin H. Gottlieb, Department of Psychology, University ofGuelph, Guelph, Ontario, NIG 2W1.