The purpose of the present study was to explore how often teachers of young children teach science concepts in kindergarten and examine the factors that influence the frequency of science teaching in early years. A theoretical model of the determinants of the frequency of science teaching in kindergarten was developed and tested using a multi-level structural equation modeling. Data for this study (n = 3305) came from the Early Childhood Longitudinal Study -- Kindergarten dataset, which included a nationally representative sample of US kindergarten teachers. The model tested in this study provided a good fit to the sample data. The results demonstrated that the number of science method courses that teachers completed, the availability of science related instructional materials in kindergarten classrooms, and teachers' perceptions of children's capacity for learning influence the frequency that teachers taught specific science concepts (e.g. earth and space, life, and physical science) in kindergarten. On the other hand, results indicated that teaching experience and teachers' perceptions of control over the curriculum do not influence how often early childhood teachers teach science concepts in kindergarten. (author abstract)