<p>Dual language profiles (DLPs) based on children’s relative levels of ability in their two languages are a compelling way of understanding the development of dual language children, yet, little is understood of what predicts different profiles. This study investigates child and family predictors of DLPs and aims to differentiate children who reach competence from those with persistently low performance. Latino children (<i>n</i> = 228; 114 females) entering school in the Northeast U.S. were classified by longitudinal DLPs (continually competent, emerging competent, low performing), based on English and Spanish proficiency at kindergarten (mean age = 6) and two years later (mean age = 8). Main predictors of DLPs were English and Spanish phonological processing and non-verbal IQ; a 1-point standard score increase in any of these 3 predictor measures was associated with a 4–11% increased probability of having a competent DLP. Findings suggest an initial low performance phase in most of the young dual language children in our study, but more than half of these perform well in the second grade (emerging competent DLP). Other low performing children continued to perform at this level two years later (low performing DLP). Empirical testing identified an exploratory, cognitive screener for low performing DLP, a potential indicator of academic risk and language delays.</p>