This article promotes a more complete understanding of social change by analyzing spatial patterns of contraceptive use in Bangladesh and the contiguous state of West Bengal in India. Multilevel analyses that control for variations in individual- and household-level correlates show an important role for cross-border influences only in those districts that share a common language across the border. The districts that are positive outliers in contraception hug the Bangladesh—West Bengal border. A map of outliers shows that the positive outliers form a contiguous band in a manner suggestive of a role for contagion.