The Great Depression and the Second World War had dramatic effects on the hospital. From 1934 to 1946 the patient population rose to around 4,100. Many nurses left to aid in the war effort, making the burden of overcrowding worse. In 1942 new regulations were created to make staffing easier. Married women were allowed to apply for jobs and auxiliary positions.

Corridor connecting Wings of Chronic Building, Coquitlam Archives C5.010-10

Following World War Two, a huge influx of veterans added to the overcrowding. The largest building at the time, East Lawn, had a maximum capacity of 921, in 1949 it held 1,445 patients. The Crease Clinic, in construction since 1929, was opened as a short-term veteran care unit. The building opened under the Mental Hospitals Act which allowed patients to voluntarily admit themselves and terminate their stay. Veterans receiving treatment here lived in accommodations on the nearby Colony Farm.

May Headridge standing and saluting in uniform 1937-43, Coquitlam Archives C5.130

Provincial Mental Hospital Graduation Class, Essondale, B.C. 1936, Coquitlam Archives C5.035