1918 Due to serious overcrowding, two more classrooms were added to the 1892 building with a regular attendance of 230 pupils.
1920 Sutherland Superior Public School—teaching 7th class subjects.
1928 Sutherland Intermediate High School began in the new buildings.
1929 Electricity and mains water connected
1930 Tar paving of the streets.
The Depression 1930s at Sutherland
During the Depression, P&C donated a pound to the soup kitchen in Boyles Hall. Lady helpers from the school worked voluntarily in the soup kitchen. The school shelter sheds were used by the homeless as sleeping places. In 1932 proceeds from a High School Operetta were distributed to 22 families in the form of "119 garments, 4 pairs of shoes and boots, 9 pairs of hose and 5 yards of flannelette.
The 1930's were tough times with many fathers involved in relief work. Whooping cough, influenza , measles and head lice ravaged the children. Sutherland Shire Council donated 92 second hand bathing costumes for children of the unemployed.
1933 to 1952 Alice Bevan commenced as Sutherland Infants' School Headmistress.
1938 Infants department triumphed with a shield and two cups for the Best Garden from the Horticultural Society.
1939 Railway to Cronulla opened. The school was ‘full'. It was hoped that the opening of infants departments at Jannali and Woronora River might ease congestion.
World War II
1939 Matron Thompson (former World War I nurse) established a first aid outpost in the infants block with an after-hours roster operated by volunteers. The room used was not electrified so it was very cold for the volunteers overnight.
1940 Tree planting ceremony to commemorate the death of Nurse Lobb (midwife) who was responsible for the delivery of local babies in the 1920s.
1942 Air Raid precautions—Parents dug trenches in the playground. Proceeds from 1942 Christmas Party spent on wire netting which was pasted onto the windows to prevent flying glass injuring students in the event of an attack. The school was an assembly point for civilians in the event of attack. Many fathers were involved in active service overseas or in the war efforts of road building to Heathcote or the garrison at North Head. Some of the fathers of children enrolled in 1943 were lost with the sinking of HMAS Perth off Java, were prisoners of war in Stalag 7A on the Danube, a POW in Malaya, or in active service in the Middle East and New Guinea.