In STEM education, a thorough understanding of the interaction of self-efficacy and metacognitive monitoring behaviors is needed to refine theories and inform the design of instructional supports for students with varying levels of motivation and self-regulation skills. We examined how students' (n = 1063) exam scores in an un-dergraduate life science course were influenced by their self-efficacy and online metacognitive monitoring be-haviors by integrating variable-centered and person-centered approaches. In a semester-long study, students' self-efficacy judgements made at the end of the semester were stronger predictors of students' final exam per-formance than those made at the beginning of the semester. Results further suggested that the influence of self-efficacy on exam scores decreased as online monitoring behaviors increased. Students' prior GPA predicted membership in three latent profiles indicated by 1) high self-efficacy with high metacognitive monitoring ac-tivity; 2) high self-efficacy with low metacognitive monitoring activity; and 3) low self-efficacy with low met-acognitive monitoring activity. Learners with high self-efficacy and high monitoring activity outperformed those with high self-efficacy and low monitoring, who outperformed those with low self-efficacy and low monitoring on exams.