Despite a growing population of students being served in Alternative Education Settings (AES) and a severe teacher shortage in AES, most traditional teacher preparation programs do not specifically address teaching in alternative settings. Unsurprisingly, teachers in these settings report being inadequately prepared to meet the complex needs of students with significant behavioral challenges. Moreover, when behaviorally challenged students exit AES, they are often at a greater social and academic disadvantage than when they enrolled. This grounded theory study followed three groups (N = 40) of teacher candidates as they completed fieldwork in one of five AES as part of a special education course at a large public university in South-eastern Pennsylvania. Analysis of teacher candidates' field journals suggested an emerging theory of 'alternative education settings as non-schools.' For these teacher candidates, familiar structures for teaching, learning, and behaviour did not apply in AES, thus delegitimizing AES as schools.