Mathematical understanding in early childhood lays the foundation for children’s later academic achievement, yet little is known about individual differences in U.S. early childhood educators’ mathematics instruction in preschool classrooms. The present study explored the range of intentional mathematics instruction occurring in early childhood programs and the relations between early childhood educators’ number-related talk and efficacy beliefs. One hour of video recordings of classroom mathematics instruction (84 videos total) were transcribed and coded from a sample of 20 lead early childhood educators teaching 3- to 5-year-old children. The results revealed significant variability across the type of mathematical content taught by educators, with a strong focus on activities with numerical content. Educators’ use of advanced numerical talk similarly varied, with some exploratory support for the hypothesis that teachers with higher self-efficacy beliefs at the beginning of the school year used more advanced number talk throughout the school year during classroom mathematics instruction. Our results suggest that educators’ mathematics instruction in early childhood varies widely, and those with lower self-efficacy for teaching may benefit from additional professional development and support. (author abstract)