Adults with and without complex support needs (CSN; e.g. with intellectual disability, autism spectrum disorder, multiple disabilities) experience benefit in many areas of their lives from developing or improving literacy skills. However, adults with CSN often face unique barriers to acquiring these critical skills, and few researchers have explored the nature of the available literacy instructional opportunities for them. In this qualitative study, we examined literacy instruction for this group of adults by interviewing 11 teachers who provide literacy instruction to adults with CSN in a variety of community agency settings about their definitions of literacy, how they structure literacy programmes, and how adults access these programmes. Findings revealed insights into the way instructors' personal definitions of literacy influenced their instructional planning and delivery and the multiple ways in which adults with CSN use literacy in their everyday lives. Barriers to effective literacy instruction were also revealed. Implications for future research and for policy and practice are discussed.