Teachers working with autistic children are at a great risk of stress and burnout, particularly in mainstream classrooms. To identify the general relationship between including a child with a mental disability and teachers' burnout and stress, as well as to discern any autism spectrum disorder (ASD)-specific associations, this study compared teachers' experiences with children with ASD, attention-deficit/hyperactivity disorder (ADHD), and conduct disorder (CD) and typical children (control group). Two comparisons with a total sample of 907 teachers were conducted: one involving mainstream teachers (three groups: ASD, ADHD, and control) and one with specialized teachers (two groups: ASD and CD). Participants completed scales measuring perceived stress, self-efficacy, perceived social support, coping, and burnout. The hypothesis that autism is specifically associated with teachers' burnout was chiefly rejected based on the results; instead, the intensity of behavioral problems appeared to be central. Clinical implications and research perspectives are discussed, particularly regarding the importance of training teachers in children's specific needs and inclusive pedagogy.