With growing emphasis on the development and use of competencies (knowledge, dispositions, skills) for training and evaluating the early childhood workforce, this study aimed to identify sources of variation in undergraduate students' beliefs and knowledge related to competencies identified by the Collaborative for Understanding Pedagogy for Infant/toddler Development (CUPID). Specifically, we examined how prior work experience with children, formal and informal, was related to students' knowledge of developmentally appropriate expectations of young children, beliefs regarding supporting parent-child relationships in center-based care, and endorsement of strict discipline and physical punishment. Results indicate that formal (i.e., in child care centers, family child care homes) and informal work experiences with children (e.g., babysitting) may relate to beliefs and knowledge in different ways. Students with formal experience indicated slightly more support for parent-child relationships than students with informal experience. Students with formal or informal experience reported less endorsement of strict discipline than students with no experience working with children. Implications for higher education programs that prepare students to work with infants and toddlers are discussed, including the importance of providing ample opportunities for undergraduates to work with children in formal settings, and to reflect on each of their caregiving experiences, early in the undergraduate program.