In 1921 due to her own illness, Lowenfeld returned to London, and came into contact with Wilfred Trotter, a pioneer of both neurosurgery and social psychology. Through this association Lowenfeld developed an interest in psychodynamic psychology as a treatment of shell-shock and learned about the work of Hugh Crichton-Miller who co-founded the Tavistock Clinic. Lowenfeld's limited medical experience in England made it easier to follow a research career. She became a researcher at the Mothercraft Training Centre studying infant health and was influenced by Truby King, a pioneer of childcare. In 1923 she obtained a Medical Research Council fellowship and Muirhead Scholarship to study at the Royal Hospital for Sick Children, Glasgow where she worked on childhood rheumatism. In 1924 she returned to infant feeding with a scholarship at the Royal Free Hospital. She also established a private practice in Queen Anne Street, London, which she kept for the rest of her working life. Alongside this research, between 1926–7 she undertook voluntary work as a medical officer at the newly opened pioneering health centre in South London, known as the Peckham Experiment, a service integrating health and social work to combat inner city deprivation.