The principal criterion of effectiveness of Applied Behavioural Analysis (ABA) in communication skills in children with Autism Spectrum Disorder (ASD) constitutes the focal point of this study. For this purpose, special educators' and psychologists' perceptions were collected and analyzed. The study was conducted through a qualitative approach. More specifically, semi-structured interviews were conducted. The interview design was based on the Curriculum for children with ASD. For the data analysis, thematic analysis was used. One of the main findings of the study is that ABA implements structured programs for teaching, which develop the basic functions of children's communication with ASD through joint attention, PECS and various other methods. In addition, it is shown that ABA programs are interconnected and each one applies a generalization of the taught skills. It is worth mentioning that the initial level of the child, the cooperation of the participants and the role modelling are of particular importance for the ABA programs. In conclusion, ABA is an effective systemic approach, which can cope with communication deficits holistically. The findings are discussed in terms of educational placement.