Four writers and their associated cluster groups were studied through content analysis of numerous biographies. These include W. B. Yeats and the Irish Literary Renaissance (1897-1906), Virginia Woolf and the Bloomsbury Group (1907-1915), Gertrude Stein and the American Expatriates in Paris (1921-1930), and Dorothy Parker and the Algonquin Round Table (1919-1928). The groups were analysed with reference to the social psychological research on group roles, structure, and interaction patterns; climate, goals and values; and cohesiveness. The writers’ development was analysed with reference to identity, differentiation, productivity and risk-taking. The analyses of all four groups-despite their diversity of membership, nationality and location-revealed remarkably similar structuring of roles and interaction patterns. The core of each group consisted of the writer and a co-dependent who hosted the group and supported the writer. Closely associated with these two roles were three others, each of which was crucial to both the task and socio-emotional functioning of the group. These included the “Irritant,” whose behavior served to focus tensions and stimulate periodic realignments within the group; the “Angel” who served to pull the group together and allow members to affirm their commonalties; and the “Sponsor” whose lack of social skills, which allowed other members to affirm their own normality, was compensated by his ability to marshal the resources to create outlets for the others’ work. Finally each group contained three additional roles which served crucial bridging functions between the group and the wider world. These included the “Odd One Out,” who had both close supportive ties to the core of the group and strong connections to other groups; the “Link,” who used his personal ties within the cultural and political establishment to promote the careers of group members; and the “Bridge” who raised sociological, political and cultural issues crucial to the core values of the group and the writings of its members. The shared values, goals and complementary patterning of roles allowed each of the groups to sustain an inordinately high and lengthy level of cohesiveness for an informal cluster group. The sizeable benefits which accrued to the four writers at the core of these groups included: (1) greatly enhanced organization and structure in both personal and professional life; (2) enhanced self-concept and public visibility as writers; and (3) increased differentiation and productivity in their writing.