There are international calls to enhance learner engagement in STEM. Further, there are international concerns about the gender disparity in interest, aspiration, and participation in STEM. These calls recognise the role that learners' motivation in, and emotional response to, STEM plays in their participation and achievement in STEM education. However, there is a lack of understanding as to what constitutes "engagement" in STEM education. In this article, we adopt an educational psychology-based definition of engagement that is influenced by motivational and emotional constructs. We review a purposive sample of student motivation and academic emotion literature to reveal pertinent insights about student STEM engagement. The review pays particular attention to findings associated with gender and offers a summary of the limited research around educational interventions informed by motivational models. This review reveals that self-concept, self-efficacy, and task value are important for STEM engagement, performance, subject selection, and career aspirations. Mastery goals are linked to high effort and persistence in STEM, while autonomy, relatedness, and growth mindsets improve STEM participation and achievement. Further, girls have lower self-concept in STEM, are less likely to hold interest and utility value, and are more likely to attribute failure to a lack of ability. Finally, negative emotional responses to STEM can form early and persist throughout schooling. These affective aspects need to be understood and explicitly addressed as part of any successful strategy to improve engagement in STEM education, and to address the significant gender equity issues associated with STEM.