An assessment is a crucial activity in the teaching and learning process, in fact, some teachers ignore the validity and reliability of assessment, whereas the ability to devise valid and reliable assessment methods to examine the student’s learning progress is the important thing to measure how effective the teaching is. This study was aimed at : (1) investigating the secondary school EFL teachers’ understanding, perspective, and classroom practice on language assessment literacy, and (2) identifying the factors that influence the secondary school EFL teachers’ knowledge and classroom practice on language assessment literacy.  This research was conducted in three different backgrounds of schools, they were public schools, vocational schools, and Islamic Boarding Schools. This study employed case study research and the theoretical framework of the Teachers Assessment Literacy Questionnaire (TALQ) proposed by Plake et al (1993). The data was obtained by questionnaire, interview, document analysis, and observations then analyzed using thematic analysis. The result showed that (1) the teachers already had very good knowledge and had positive perspectives regarding to assessment literacy. their knowledge, perspective and classroom practice involved: a) the relevance between assessment method and instructional objectives, b) the development of assessment and management of learning outcomes, c) the benefits of assessment d) the form of assessments e) the ranking of assessments results f) unethical action in conducting assessment. (2) The factors that influence teachers’ knowledge perspective and classroom practice on language assessment literacy were: a) the participation of secondary EFL teachers in the training activity, b) teaching experiences, c) teaching difficulties, d) the support from educational institutions, and e) assessment materials were obtained in the university. This study might contribute to the teachers in carrying assessments following standards, and for educational institutions, should be aware of the teachers’ competency to increase teachers’ competence and enthusiasm in carrying out better assessments.