This study explored how a scenario-based (SB), one-semester professional development program influenced the instructional practices of preservice early childhood mathematics teachers. The participants completed a 15-week program in which they engaged with modeled in-class teaching experience and subsequently answered a number of questions that prompted them to consider possible ways of reacting in similar, everyday interactions with children. The findings indicate that the SB activities enhanced the teachers' perceived instructional practices and their motivation to use student-centered instruction when teaching early mathematical concepts to children. By contrast, results indicate that the preservice teachers developed lower scores on the teacher-centered practices construct after their engagement in the SB professional program. This research inspired the recommendation that early childhood teachers should find balance in focusing on direct math content with supporting children's self-efficacy and emotional development through child-centered instruction.