Multiraciality and mixed-race students have long been overlooked in K12 education discourse despite a significant increase in the number of students identifying as more than one race. Research that does address Multiracial students tends to focus on multiracial identity development of college students. However, educators and K12 school leaders must engage critically with how theoretical abstractions like 'racial identity' are being parsed and adopted in school policies, particularly as it pertains to mixed-race students. Having a deeper understanding how Multiracial identity is conceptualized and deployed makes it possible for K12 practitioners to better appreciate how race and racial identity operate in schools. This literature review for K12 practitioners highlights theories and assumptions about identity that have gained acceptance in K12 education--cognitive identity development models; social identity theory; and the uncritical adoption and use of racial categories. The literature review presents limitations and challenges these theories pose for understanding Multiracial identity in a K12 context. Lastly, this work suggests a postpositivist realist theory of Multiracial identity be used in education and the implications of such for K12 practitioners working with Multiracial students and families.