Instructors make assessment decisions based on their knowledge and experiences. Assessment practice is an essential element of instruction, and the outcomes of assessments have a broad impact on both students and instructors. Efforts to provide strengths-focused, relevant professional development support regarding assessment are enhanced by greater understanding of the complex nature of assessment practices. In this study, the Teacher Assessment Literacy in Practice (TALiP) framework was used to guide our investigation of one biochemistry instructor's assessment literacy, relevant to her integration of a biochemistry threshold concept, the physical basis of interactions (PBI), into her course. Qualitative framework analysis was used to examine classroom artifacts and interview data to reveal that community support and self-reflection influenced the instructor's enactment of specific assessments aligned with her instructional goals. Additionally, the instructor was seen to leverage assets to develop her assessment literacy within a single semester.