This chapter addresses the issue of sample selectivity in underemployment by investigating determinants of labor force participation. The labor force participation literature points to three major groups of factors that determine participation in the labor force: nativity and migrant status, human capital, and family considerations. Since education increases productivity, and consequently earnings, people with higher education experience a high opportunity cost by staying away from the labor force. Labor force participation is expected to increase with higher levels of education. Another family factor in labor force participation is the concept of tied migration. Migration status is a significant predictor of labor force participation in 1990 for all but Filipino women, showing older migrants and US-born women as more likely to be in the labor force compared to more recent migrants. High school graduation is a positive and significant influence on male labor force participation across ethnic groups and time.