This chapter reviews with relations of alliance: the functional meaning of the household affiliations occasioned by marriage, including the specific aspects of marriage contracts in rural Japan which have a direct bearing on the actual social and political organization. The rise or fall in the relative status of a household in the community is clearly reflected in the network of marriage relations of that household. The economic implications of marriage are not confined to the shift of labour force, but extend to the inter-household relationships that are created by the marriage. The scope of the marriageable field is determined largely by the economic and social status of a household within a village community, and the local economic situation in which a village is involved. A similar situation can be created by marriage among the members of any corporate group formed by households of relatively equal status.