Two types of Mandarin immersion programs for elementary age children are growing in popularity: the early total (90/10) program model and the partial (50/50) model; however, little empirical data exists on student learning in either program type. This paper reports on a multi-year research study of K–5 students who participated in the early total Mandarin immersion program. Findings show achievement in English reading and math that is commensurate with, and at times better than grade-level non-immersion peers’ achievement in the same school, district, and state. There was also evidence of a “math advantage” for the Mandarin immersion learner group both in Grades 3 and 5. Beyond academics, the majority of Grade 5 students demonstrated proficiency in Mandarin at Intermediate levels with listening and speaking skills outpacing character writing and reading. This finding suggests a need to further explore character literacy development to better understand best practice for English-proficient children in the U.S.