This study examined program practices in a state-funded preschool in Northern California that had recently added a new assessment to its existing tools to measure and evaluate preschool students' school readiness. The study found that teachers might need a range of supports when given the opportunity to integrate a new assessment tool into their practice. Although teachers generally value the information from these tools, more opportunities for formal training, ongoing supervisory support, and collaboration with their colleagues—both within and across classrooms and grades—can help them to act effectively on the information.