One of the vital and critical roles of the teachers is the ability to assess students‟ performance; yet many teachers are not well-prepared for this demanding task. Most of the teachers believe that for implementing assessment concepts and making decisions about assessment, they need assistance and improvement (Mertler and Campbell, 2005). So the present study aimed at measuring and describing the levels of assessment literacy of Iranian high school and language institute teachers while taking into account the role of gender and years of experience. To do so, one hundred EFL teachers (50 high school teachers and 50 language institute teachers) took part in the study by completing the Classroom Assessment Literacy Inventory or CALI (Mertler, 2002) which is adapted from the Teacher Assessment Literacy Questionnaire (1993). The results of the study revealed that: a) there is a statistically significant difference between the high school and language institute teachers regarding their assessment literacy level, while the assessment literacy of both groups are far below the standard level; b) Iranian male and female teachers are statistically different from each other regarding their assessment literacy, with the males outperforming; and finally c) a statistically significant difference exists among different age groups regarding their assessment literacy, the higher the years of experience the higher the level of assessment literacy. The findings can be of assistance to teachers‟ professional development
