Throughout our lives, we go through numerous changes. These changes are called transitions and are an integral part of our lives. Most of them are experienced as stressful. One of the first transitions a child encounters is entering kindergarten. Children with developmental difficulties are often exposed to a higher number of transitions that disrupt established routines and lead to changes in behavior. This is even more pronounced in children diagnosed with autism spectrum disorder due to the specific nature of the diagnosis. This paper presents a case study of a boy diagnosed with autism spectrum disorder in the process of transitioning from a Special Education Program for children with autism spectrum disorder in early and preschool age from the Center for Autism to a regular kindergarten group. The aim of this study is to design, implement and evaluate a transition program for a child with a diagnosis of autism spectrum disorder and other participants in the transition process. The transition process lasted for 8 months. Expert support was provided in the kindergarten group at the Center for Autism - preparation for transition and at Zvončić Kindergarten - the actual transition process and support after the transition. The progress of the boy was monitored at two time points - initial and final. The entire transition process was also evaluated. Based on the results obtained, guidelines and protocols for the transition were developed for the child, parents, educators, and peers.