This publication is derived from the proceedings of the Third Canadian Conference on Research in the Rheumatic Diseases, sponsored jointly by the Canadian Rheumatism Association (the professional organization) and The Canadian Arthritis and Rheumatism Society (the voluntary association). Like the previous conferences on Research in Rheumatic Diseases held in 1955 and 1960, this gathering served as a meeting ground for the exchange of information and the re-examination of the correlations suggested by the observations gathered and arranged by investigators using differing tools and hypothetical methods.