A study of human resource management practices in 249 U.S. affiliates of foreign-based multinational corporations (MNCs) shows that in general affiliate HRM practices closely follow local practices, with differences among specific practices. The degree of similarity to local practices is significantly influenced by the method of founding, dependence on local inputs, the presence of expatriates, and the extent of communication with the parent. In addition, sharp differences are revealed among affiliates of Canadian, Japanese and European MNCs, suggesting strong country effects. Together, these findings support the view of MNCs as composed of differentiated practices, which in turn are shaped by forces for local isomorphism and for internal consistency.