Despite growing diversity among Asian Americans, little attention has been given to the diverse experiences and outcomes of Asian American subgroups in science, technology, engineering, and mathematics (STEM) fields. Using a nationally representative data set, High School Longitudinal Study of 2009 (HSLS:09), this study examines Asian American students' various pathways of entrance into STEM majors by college selectivity. Results show different patterns of STEM major selection among Asian ethnic subgroups that are not uniformly applied to all types of college selectivity, thereby revealing the heterogeneity within Asian American populations and suggesting the peril of the monolithic stereotype of Asian American students in STEM fields. Analyses further disclose that disparities of STEM major selection among Asian ethnic subgroups can be partially but not fully explained by high school math achievement.