Past research has documented compromised development for teenage mothers' children compared to others, but less is known about predictors of school readiness among these children or among teenage fathers' children. Our multidimensional measures of high and low school readiness incorporated math, reading, and behavior scores and parent-reported health. Using parent interviews and direct assessments from the Early Childhood Longitudinal Study-Birth Cohort, we predicted high and low school readiness shortly before kindergarten among children born to a teenage mother and/or father (N≈800). Factors from five structural and interpersonal domains based on the School Transition Model were measured at two time points, including change between those time points, to capture the dynamic nature of early childhood. Four domains (socioeconomic resources, maternal characteristics, parenting, and exposure to adults) predicted high or low school readiness, but often not both. Promising factors associated with both high and low readiness among teen parents' children came from four domains: maternal education and gains in education (socioeconomic), maternal age of at least 18 and fewer depressive symptoms (maternal characteristics), socioemotional parenting quality and home environment improvements (parenting), and living with fewer children and receiving nonparental child care in infancy (exposure to adults). The findings preliminarily suggest policies that might improve school readiness: encouraging maternal education while supplying child care, focusing teen pregnancy prevention efforts on school-age girls, basic socioeconomic supports, and investments in mental health and high-quality home environments and parenting.