Building upon the research findings in an earlier ACT Research Report (Westrick, 2016), this study used data from 119,131 students at 26 four-year institutions to make comparisons between STEM majors earning semester GPAs of 3.0 or higher and their STEM peers earning semester GPAs less than 3.0. The results indicate that the higher-performing students entered college with higher mean ACT scores and HSGPAs than did their peers, though their measured interests were quite smaller. For STEM majors who earned semester GPAs of 3.0 or higher consecutively in semesters five through eight, their mean ACT STEM scores exceeded the ACT STEM benchmark of 26. High school students considering a STEM major in college may benefit knowing the level of precollege academic achievement required to perform at a high level in a STEM program in college. [For the previous 2016 report, "Profiles of Persisting Fourth-Year STEM Majors. ACT Research Report Series 2016 (5)," see ED573721.]