In this article, the authors analyze the ways literacy integration evolved in a multi-year interdisciplinary after-school program that supports youth through a focus on literacy, physical activity, and health. To deviate from the increasingly siloed assumptions around literacy education and attend to a more interdisciplinary, integrated perspective, the authors theorized literacy across multiple theoretical perspectives to examine 5 years of program implementation in three different sites (New York City, Los Angeles, and Paraguay) with culturally and linguistically diverse youth (ages 9-14), program leaders, and researchers. Drawing on assemblage theory to guide the analysis, the authors sought to identify the multidimensional (im)materialities that converged to produce evolutions of literacy integration in an after-school program. Analyzing data for assemblaging factors that produced youths' literacy engagement differently throughout program years led to identifying three emergent assemblages that frame the findings: (1) Well-intentioned literacy integration but more complex than expected, (2) Imprints of schooled literacy with sociocultural emergence, and (3) Community- and youth-centered literacy integration. The authors conclude with implications for educators and after-school leaders seeking to integrate literacy with interdisciplinary aims.