The paper consists of two parts. The first reviews an appraisal of the contemporary theories of international migration. Among older theories, the push-and-pull model, the segmented labour market theory, world-system theory, and the political economy model are examined as macro-level explanatory approaches, and, at the micro-level, the neoclassical economic (otherwise known as rational choice) theory, human capital theory, new economics of migration, migration network or social capital theory, and the cumulative causation model are examined. The second part presents an encompassing theoretical approach, migration as structuration process, and identifies its advantages over other models. This approach is then comparatively applied to eight immigrant groups chosen as case studies.