This secondary analysis study examined patterns, predictors, and outcomes of dual language learners’ (DLLs’) development in Spanish and English. Research Findings: Latent profile analysis identified three groups of DLLs: Balanced Bilinguals (54%), English-Dominant Bilinguals (25%), and Spanish-Dominant Bilinguals (21%). These groups had fairly comparable Spanish skills at Head Start (HS) entry but showed distinct learning patterns in English and Spanish during the 2.5 years in HS and kindergarten (K), which resulted in group differences in dual-language skills at K. When their home and classroom environments were compared, Balanced Bilinguals had more Spanish exposure than English-Dominant Bilinguals and more English exposure than Spanish-Dominant Bilinguals. Spanish-Dominant Bilinguals generally had more Spanish exposure at home and in the classroom, less English exposure at home, and had parents with lower English proficiency. English-Dominant Bilinguals had fewer home literacy materials in Spanish and had fewer opportunities for Spanish exposure in their first HS classrooms. Balanced Bilinguals presented the highest K achievement; the other two groups showed comparable skills. Practice or Policy: This study demonstrated variations in dual-language learning among DLLs in HS and indicated the need for tailored strategies that address the unique needs of diverse DLLs presenting varying proficiency in their two languages. (author abstract)