Migration flows do not yield themselves easily to any particular theoretical framework. This was probably why Davis (1988) was led to comment that migration “has been opaque to theoretical reasoning in general” and Massey et al. (1998) and Massey and Taylor (2004) observed that migration lacks a common theoretical framework (also see Arango 2000). Yet, over the years, the World-System (WS) approach (see particularly Wallerstein 1983, 1988; Chase-Dunn and Hall 1997) has gained increasing acceptance in the field of international migration (Portes and Walton 1981, Straubhaar 1988, Massey 1998). By treating migration as inherent to the capitalist world economy, the WS school holds the view that it reinforces the global inequality between the core and the periphery. The change in the composition of migration toofrom the unskilled to the semiskilled and the skilled, and the feminization of migration-seems to correspond to changes in the world capitalist economy such as a deepening of capital penetration and flexible accumulation. However, the world-system approach is not without its limitations, and some refinements appear to be called for, as has been attempted in this chapter.