This review article examines mathematics identity as a multidimensional and context-sensitive construct that helps explain students’ relationships with mathematics beyond test scores and cognitive performance. Mathematics identity is discussed at the intersection of learners’ self-perceptions in mathematics and the social experiences they live through while participating in mathematical practices. Building on major strands in the literature, the paper synthesizes psychological and subjective perspectives such as competence and value-related beliefs, sociocultural perspectives such as participation, belonging, and recognition in communities of practice, and narrative and discourse approaches that emphasize identity as continually rewritten through experience and storytelling. A prominent explanatory framework highlighted in the review conceptualizes mathematics identity through three components: interest, competence and performance beliefs, and recognition by significant others such as teachers and peers. The article also summarizes evidence linking mathematics identity to achievement, engagement, motivation, persistence, and longer-term orientations toward advanced coursework and STEM pathways. Finally, it discusses how identity is shaped by classroom norms and interactions, and offers instructional implications: learning environments that make students’ ideas visible, distribute participation more equitably, treat errors as productive, and recognize students for their mathematical thinking can strengthen mathematics identity; therefore, identity-supportive pedagogical principles should be explicit targets in teacher education and curriculum development.