This study examines how, for emerging adults attending residential colleges, family incomes and the SES composition of high schools are jointly associated with academic behaviors in college. Using a one-time survey, daily surveys, and additional data collection on high school SES composition, this study measured 221 college students’ (17-25 years old) SES backgrounds and academic behaviors. Findings indicated that three academic behaviors (study time, in-class engagement, and help-seeking) were predicted by an interaction between family income and high school context. Among students who attended high schools that serve many low-income students, higher family income was significantly associated with more beneficial academic behaviors in college; among students who attended high schools that serve few low-income students, there was no association between family income and academic behaviors. Results indicate that colleges may need to be especially prepared to support students from lower-income families who matriculated from lower-SES high schools.