Despite the recent interest in examining the teacher assessment literacy in general, teachers’ writing assessment literacy (WAL) remains almost an unexplored area. When considering the issue in the Iranian EFL context, it becomes more important. Exploring the context shows the lack of a country-wide, systematic study on the EFL teachers’ WAL. Considering this gap, this study set out to investigate the Iranian EFL writing teacher’s knowledge, beliefs and practices regarding writing assessment. To achieve this goal, an adapted version of Crusan's (2016) writing assessment literacy questionnaire was used in this study. The questionnaire was sent out to major state universities in the country. Finally, the researcher received back 118 questionnaires. Finding of the study illustrated that although writing instructors had a positive attitude toward writing assessment and were aware of some basic concepts of writing assessment, their level of assessment literacy was not reflected in their practice, particularly in rubric use. The results further showed that the teachers need to develop sound and clear conceptual understanding of WAL as well as the ability to use the knowledge in practice in the actual context of writing assessment. Overall, it can be argued that in the absence of a systematic pre-service and in-service writing assessment training programs, the teachers rely on their individual expertise developed throughout their years of practice. The results of the study have several pedagogical implications for teacher educators to improve EFL teachers’ writing assessment literacy.