EN
The article deals with the theoretical foundations of PECS (Picture Exchange Communication System). It is an example of supporting and alternative methods of communication – AAC (Augmentative and Alternative Communication). It can be both a supportive and alternative communication system. The strategy of acting for PECS is based on the principles of applied behaviour analysis – ABA (Applied Behaviour Analysis), the verbal behaviour approach and the assumptions of the Pyramid Approach to Education. Theoretical consolidation of PECS is supported by the results of scientific research conducted in the field of applied behaviour analysis. Verification of the theoretical concept through empiricism is the strength of the PECS method.