Young children’s mathematic skills are important predictors of later school success. Yet, we know little about the mathematics exposure children receive in early childhood classrooms. Most early childhood education settings use a published general curriculum, and instruction is likely driven in part by these curricular materials. Therefore, we examine the mathematics activities in 15 comprehensive preschool curricula. We describe the prevalence of mathematics as well as the mathematical content, intentionality, and multi-step (extended) characteristics of these activities. We find that mathematics comprises about 14% of the total activities in the curricula, ranging from 5% to 90%. We find wide variation in the content, intentionality, and depth of the activities. Some curricula cover a more diverse range of content; others focus on only one or two mathematics domains. Most of the mathematics activities across the curricula do not involve more than 1-2 steps, and about 20% do not provide mathematical guidance for the teacher and students. To enhance mathematical learning, more attention is needed to the mathematics included in early childhood curricula.