The current study uses the data of Education Longitudinal Study of 2002 (ELS: 2002) to examine patterns of choice of STEM majors in college by students from different family socioeconomic (SES) backgrounds. Logistic regression results show that low-SES students are disadvantaged in the pursuit of STEM majors. Higher family SES compensates for negative predictors of STEM enrollment, such as gender and race, and strengthens the effect of positive predictor, such as math preparation. The gender and racial gaps in STEM enrollment narrows for students from higher SES families, and the positive correlation between math preparation and STEM enrollment strengthens with the increase of family SES, except for lowest SES students. Family's immigrant background does not play a role in choice of STEM major. Results indicate that low-SES students may not possess the information and/or skills necessary to make well-informed decision of STEM enrollment so as to maximize their opportunity to succeed in college.