In this paper, we explore second language (L2) teachers’ cognitions regarding the initial assessment of adult learner literacy in their strongest language. Instruction can thus be adapted according to what is stipulated in the curriculum and syllabus. The literacy assessment is conducted in the student’s strongest language with assistance from an interpreter, translated decoding and reading comprehension tasks and concerns assessment of learners with little or no prior education. Questionnaires and interviews with L2 teachers reveal great variation based on four categories of teacher knowledge, namely, Subject matter knowledge, Knowledge of students, Pedagogical knowledge, and Knowledge of educational contexts. These four categories were partly intertwined with each other and both a resource and a deficit perspective emerged. The teachers’ cognitions regarding the concept of literacy, the value of initial L1 literacy assessment and students’ prior literacy and multilingual resources, as well as its potential for instruction planning were diverse. This may have significant implications for what emerges in initial assessments of a student's L1 literacy. In turn, this affects the validity of the assessment and, ultimately, the quality of education.