The Third Workshop on Recognition and Action for Scene Understanding (REACTS) is a satellite event of the 16th International Conference of Computer Analysis of Images and Patterns (CAIP) which will be hold in the Mediterranean Conference Centre at Valletta, Malta, September 5 2015. Scene Understanding has become a popular topic in Computer Science which combines abilities such as perception, analysis and interpretation of both indoor and outdoor scenes. Hence, it involves joining efforst and sharing knowledge from different research areas such as Computer Vision, Pattern Recognition, Machine Intelligence, Software Engineering and Cognitive Sciences.