This chapter analyses immigration trends and labor market situations into an analysis of the economic assimilation of Asians in the United States. It examines the microlevel determinants of four forms of underemployment – unemployment, part-time work, working poverty, and job mismatch – for white, Indian, Filipino, and Vietnamese men and women in 1980 and 1990. The human capital theory views the acquisition of skills and knowledge as investments of resources on people for future economic payoffs. Demographic processes and changing labor markets are expected to alter the influence of human capital investments on labor market status. The chapter examines a combination of family and household factors can undermine labor market activity. Economic assimilation is achieved when immigrants have the same economic opportunities as native-born workers, and the returns to human capital investments in terms of earnings and occupational status are the same for both groups.