Song is an inequality scholar of family diversity, gender, and sexuality (LGBTQ+) in the global context. More broadly, his research unravels the important role of family in the (re)production and reduction of social inequality and health disparity. He studies inequality at the intersections of multiple systems of privilege and oppression, including those based on gender (sexism), sexuality (heteronormativity), race/ethnicity (racism and nativism), and social class (classism).

Most of Song’s work applies quantitative methods to large-scale representative data in drastically different socio-political contexts, such as the U.S. and China. His work has been published in leading peer-reviewed journals, including Demography, Journal of Marriage and Family, Social Science Research, and Population Research and Policy Review.

Currently, Song works on two research directions: 1) QUEERFAMILY: based on dissertation, he explores the social organization of family life among sexual minorities in the U.S., such as assortative mating, the division of labor, and mental health; 2) GLOBALFAMILY: he studies family diversity, gender, and inequality in China and East Asia, exploring the role of (college) education, state policy (e.g., household registration system or hukou and One Child Policy), and demography (e.g.,. cohort change).