Students must master content for success in science, technology, engineering, and mathematics (STEM), but "how to" is rarely taught in college. Faculty are reluctant to sacrifice class time, believe such instruction is remedial, or assume students possess or will attain these skills independently. To determine whether explicit instruction would improve skills and performance by first-year undergraduates likely to major in STEM, we invited all students in an introductory biology course to participate in an 8-week Co-Curricular (CoC) program. Students who participated improved time management, used more methods to plan and organize their study, and used a variety of active-learning strategies. A validated model was used to predict students' probability of achieving a "C+" or better in the course. The model, based on 5 years of data, used students' demographic characteristics and previous academic performance to provide a measure of their preparedness. Students with low and medium preparedness who participated in CoC performed better than those who did not participate. All students who participated were retained in the course compared with 88.7% of students who did not participate. Specific behavioral changes at the start of STEM gateway courses can dramatically improve student metacognition, retention, and academic performance, particularly for students underrepresented in the discipline.