Guided by the family investment model, family process model, and componential model of reading, this study examined underlying mechanisms linking family socioeconomic status (SES) to reading comprehension. Participants were 682 Chinese third graders (Wave 1, M[subscript age] = 9.31 years, 338 girls) randomly recruited, and they were followed up after 1 year. Structural equation modeling revealed that higher parents' education was related to more books in the home and higher levels of positive family relationship, which was associated with better language skills directly or indirectly through stronger reading interest--better language skills ultimately linked to better reading comprehension. No significant indirect pathways were found from family income to reading comprehension. The mediating pathways were similar for children with different parental migration statuses.