Self-efficacy is essential to motivation and learning. Compared to students with weak self-efficacy for academics, students with strong self-efficacy have higher motivation, make greater effort, persist longer, and achieve more. Unfortunately, struggling learners with weak self-efficacy often avoid academic tasks or give up prematurely, reducing the likelihood of academic success. Because tutoring usually occurs in one-to-one or small group situations, adult tutors are in an excellent position to enhance struggling learners' self-efficacy which, in turn, can improve academic outcomes. To achieve this, tutors need to understand the importance of self-efficacy, its sources, and how to strengthen weak or flagging self-efficacy. To assist tutors in strengthening learners' self-efficacy, this article discusses (a) the importance and sources of self-efficacy, (b) instructional principles derived from these sources, and (c) topics for future research.