Lowenfeld realised that ‘Play’ was the medium through which children worked out their emotional conflicts. She recognised that it was a cognitive process which could be analysed (in a non-Freudian way) to understand and deal with behaviour problems and also perhaps help them to develop. She developed the then new concept of non-verbal communication, and methods and tools for using «Play» as therapy and as a therapeutic and analytical tool. This work follows on from her classic book Play in Childhood was published in 1935.