This study investigated the effects of labels on preschool teachers' attitudes (i.e. openness) towards the strengths and difficulties of autistic preschool students in the mainstream setting. It also examined the differential effect of disclosure of a specific or a generic label, and the teacher-related factors influencing their attitude. Sample consisted of 106 mainstream preschool teachers (mean age = 30.37 years, "SD" = 8.85) from Singapore randomly assigned to one of three groups: "Autism Spectrum Disorder Label", "Special Needs Label", or the "No Label" group. Participants read a total of 15 vignettes depicting characteristics of autistic preschool students as strengths, difficulties, and neutral behaviours. They then rated their openness towards the featured student and complete a measure of their autism knowledge. Results indicated that the disclosure of a student's special needs label improved teachers' attitudes towards the difficulties faced by autistic students compared to when no label was disclosed. Teachers' knowledge of autism and whether teachers had experience teaching autistic students predicted the openness rating. This study has implications for parents regarding diagnosis disclosure, for the whole educational system when designing diagnosis and information transfer and the importance of professional training among early childhood educators.