This three-year longitudinal study examines the development of four Chinese novice EFL teachers' classroom assessment literacy, which refers to teachers' knowledge of and abilities to conduct classroom assessment and is reflected in their planned and improvised assessment practices. The dataset includes 26 classroom observations, 48 interviews, and 171 participants' journal entries. Data analysis following the paradigmatic analytic procedures reveals three developmental stages for novice teachers' classroom assessment literacy: the first stage features the acquisition of practical techniques for planned classroom assessment; the second stage allows novice teachers to gain a growing awareness to connect planned classroom assessment to teaching objectives, but the usefulness of assessment results in teaching adjustments was only confined to an improved plan of a future teaching situation; in the third stage, novice teachers are more inclined to conduct improvised formative assessment in teaching which shows immediate assessment-driven teaching improvements in response to dynamic classroom interactions.