This article attempts a tentative explanation of structural differences and similarities among contemporary Irish communities as described by anthropologists. Two ideal-typical case studies of community development are described in which the role of landlord-tenant relations is critical. In the first type, exemplified by County Clare, the structure of social relations was affected by disincorporating processes active through the colonial period. In the second type, exemplified by Teelin, a fishing community in southwest Donegal, such processes were much mitigated by forces both ecological and social. These ideal developmental types shed light on the contemporary rural Irish landscape, as well as on the effects of landlord-tenant relations on the social organization of local communities generally.