This article explores teachers' assessment knowledge and practice through a narrative inquiry of a college EFL teacher, Betty (pseudonym), in the People's Republic of China. Drawing on Crites' (1971) notions of "sacred stories" and "secret stories" in teachers' professional knowledge landscapes (Connelly & Clandinin, 1995), it examines Betty's account of her experience of assessment reform. This account comprises three stories involving her colleagues and students. Following Connelly and Clandinin's (2006) three strands of narrative inquiry, this article discusses three structural conditions of teacher knowledge, "temporality", "sociality", and "place", and their effects on teachers' knowledge construction of assessment. We argue that teachers' prior assessment experience will affect their current practices and future plans for assessment (temporality); power relationships in teachers' workplace will greatly influence their assessment decision-making (sociality); and the specific contexts in which assessment takes place will affect teachers' sense of security and therefore the effectiveness of the assessment (place). The findings highlight the recognition of teachers' agency in assessment practice, the importance of negotiation with teachers of the reform policies, and the urgent need for professional development. (Contains 1 table, 1 figure and 6 footnotes.)