Research Findings: Assessment and accountability have been given prominent attention in the field of education in recent decades. Educators have been debating what assessment is, how it is practiced in school, and how it is used for accountability purposes. A case study was conducted of the assessment practices in a Hong Kong preschool to understand the issues of assessment and accountability. This study investigates changes in assessment practices and explores implications for assessment and accountability. This research adopted various qualitative data collection methods, including interviews, site observations, collection of documents, and review of personal notes. The findings showed that there was a paradigm shift of assessment practice from an outcome-oriented approach to a process-oriented approach. Results revealed 4 major changes in the new assessment approach that involved the choice of assessment tools, the planning procedures, data collection methods, and new assessment activities. The major changes were built on the idea of assessment for learning and the strength of school capacity supporting self-improvement. The development of a culture of collaboration and professional learning communities helped to enhance teacher development and build school capacity. Practice or Policy: This study urges the improvement of process-oriented assessment, school capacity, and the use of assessment data to understand the impacts of the new accountability system. The study supports a more balanced approach of combining school internal capacity and external systems to uphold school accountability and advocates the use of process-oriented assessment in early childhood education. (Contains 1 table and 1 figure.)