Abstract Bilingual children often engage in code-switching (CS) or switching between languages. Research indicates CS shifts as a child's L1 and L2 proficiency change, yet little is known about how these patterns unfold in structured academic tasks. This study examined CS in 195 Spanish-speaking English learners on narrative recall tasks in Spanish and English from kindergarten through second grade (4;9–9;1; 57.9% female). In kindergarten, children switched into Spanish on the English task, but by second grade, they switched into English on the Spanish task. The patterns of CS paralleled shifts in relative proficiency: weaker skills in English predicted switching into Spanish, whereas weaker skills in Spanish predicted switching into English. These findings highlight CS as a dynamic reflection of developing bilingual proficiency.