ABSTRACT Development of professional competencies is a key outcome of undergraduate programs preparing practitioners to work with infants and toddlers. Competencies for working with young children were examined among 1300 undergraduate students at 12 universities. Students completed a series of online questionnaires indicating their knowledge, beliefs, and hypothetical practices with young children; end-of-semester scores were analyzed using linear regression. Having had a practicum course is associated with more positive dispositions for supporting the development of teacher–child relationships, building partnerships with diverse families, guiding children’s behavior, and fostering development and learning. Further, we examined development of dispositions over the course of a semester based on undergraduates’ current and past practicum experiences. Implications for programs who prepare infant and toddler practitioners are discussed.