We investigated the factors that may help understand the differential rates of language development in the home language (i.e., Spanish) of Latino preschoolers with specific language impairment. Children were randomly assigned to either bilingual or English-only small group interventions and followed from preschool to kindergarten. Predictors of Spanish growth included the language of intervention, the child's level of language development or severity, the child's socioemotional skills, and the child's level of English use. Spanish performance outcomes were assessed over time using a series of longitudinal models with baseline and posttreatment measures nested within child. Children demonstrated growth on Spanish outcomes over time. The language of instruction and the child's level of vocabulary and socioemotional development at baseline were significant predictors of differences in rates of growth in the home language. Clinicians may need to take into consideration these factors when making clinical recommendations.