PROJECT SUMMARY Mathematics are essential skills for daily living as well as academic success and future employment. Yet in the U.S., educational disparities exist in children’s math skills from school entry through K-12 education. One possible contributor to differences at the start of kindergarten could be differential verbal inputs about mathematics by parents – also known as “math talk.” Research, almost exclusively with mothers and in English, finds that math talk in early childhood contributes to math skills in preschool and kindergarten. However, little is known about math talk by fathers, math talk in Spanish or bilingual English-Spanish parent-child interactions, or combined caregiver math talk and their effect on math skill development. Capitalizing on the NICHD-funded Baby Books 2 project, a bilingual (English-Spanish) longitudinal parenting intervention for low-to-moderate income first-time parents and their young child, we explore the amount and types of math talk in recorded mother-child and father-child play and reading interactions at 9, 18, 24 and 30 months. Specifically, we compare, through observational coding and textual analysis of transcripts, the frequency, variety, and types of math talk that parents engage in with their very young children, in English and Spanish. We also assess how mothers’ and fathers’ math talk, independently and together, contribute to children’s math skills assessed at 38-46 months, after controlling for parental (e.g., nativity, education, mental health) and child (e.g., temperament, language skills) characteristics. This research will increase our understanding of early parental contributions to young children’s early math skills and, potentially, identify the types of verbal inputs that are most supportive for children’s school readiness.