Fleck did his psychiatric residency at Johns Hopkins Hospital in Baltimore, Maryland,[2] where he first met his lifelong colleague Theodore Lidz.
Fleck and Lidz "worked from the late 1940s on to change the direction of psychiatry from the purely psychoanalytic to a specialty incorporating social-scientific methodology, medical, behavioral, neurological and public-health factors, and especially familial considerations.
[6] In addition to his research, professorial, and supervisory roles at the school of medicine, Fleck was also chief psychiatrist at both the Yale Psychiatric Institute and the Connecticut Mental Health Center.
[7] Fleck officially retired from Yale in 1983 but continued to publish and to consult on colleagues' cases until a few months before his 2002 death.
Together, the Flecks were campaigners for legalized birth control and abortion, participating in the activism that led to the landmark 1965 Supreme Court decision Griswold v. Connecticut.
Louise Fleck had grown up in Nome, Alaska among other places, and had traveled and worked internationally before and after World War II receiving a BA (honors) in Spanish from the University of Washington.