Students with intellectual disabilities (ID) display an extremely wide variety of skills in the field of literacy, and the ability to read and write are central learning aims in the education of students with ID. It is vital to gain detailed knowledge on the literacy skills of students with ID in order to plan instruction, create learning environments, implement educational policies or funding models and specify future fields of research. However, there has been little research into the prevalence and variation of their reading skills. The present study assessed the reading stages of 1629 school-aged students with ID regardless of aetiology (age 6-21) in Bavaria, one of the largest regions in Germany within a randomly chosen and representative sample. Teachers described the reading and writing stages of their students in a questionnaire following the developmental model of Frith. Results indicate that 29.3% do not read at all, 6.8% read at a logographic stage, 31.9% at an alphabetic and 32% at an orthographic level. Writing achievements are lower on average. We analyze and discuss the determinants of literacy in this sample with regard to the sociocultural background of students with ID and draw conclusions for teaching and school policies. (Contains 4 figures and 4 tables.)