In this contribution, the authors situate the development of Bowlby's attachment theory against the background of the social, cultural, and scientific developments in interbellum Britain. It is shown that fairly early in his life Bowlby adopted one fundamental idea-that an infant primarily needs a warm and loving mother, and that separations from the mother are potentially damaging-and never substantially changed that basic notion in later years. Bowlby's first and foremost goal-and his lifelong undertaking-was to convince certain others (e.g., orthodox psychoanalysts, psychiatrists, clinicians, and medical doctors) of the importance of this idea by theorizing and gathering empirical evidence. Bowlby's view of mother love deprivation as the main source of maladjusted behavior was at variance with the views of many practitioners and theorists, but it was by no means fully novel and original. The authors show that Bowlby took inspiration from various persons and groups in British society with whom he shared basically similar views.