While writing these books, Susan had re-entered the world of psychoanalysis. The possibility of treating children with psychoanalytic methods was now much discussed at the meetings, given strong impetus by a new figure on the scene, Melanie Klein. She had established herself in Berlin but found little sympathy for her ideas there and so, in 1926, was pleased to accept an invitation from Ernest Jones to settle in London. During a previous visit to England, she had visited the Malting House School and got on well with Susan Isaacs.
Susan now became an enthusiastic advocate for Kleinian ideas which put great emphasis on the role of infantile fantasies in the development of personality and psychopathology. In 1927, she engaged in a further personal psychoanalysis with Joan Riviere, an analyst herself much influenced by Melanie Klein. By the end of the 1920s Susan had become a fully trained analyst for children as well as for adults.