The concept of identity has been used to interrogate a wide range of topics about children's learning in the content areas, including learning in literacy, math, and science. Despite this, there is a paucity of attention to how the construct of identities is conceptualized across content areas. This systematic integrative review aims to develop an empirically grounded view of how identities are conceptualized in childhood across content areas and to consider the feasibility of a shared conception of content area identities. To do this, the review examines 66 articles on content area identities in early childhood and childhood (birth through Grade 5). Findings show diverse theories are used to examine content area identities in children and at the same time significant consensus in the underlying assumptions about what content area identities are and how they develop. These findings suggest that researchers move away from the current siloed approach to content area identity research and toward a more connected field of study.