Both settlements remained small from the Middle Ages through the Early modern period, and did not see significant population growth until the 20th century.In 1879 the Frederikssundbanen was extended through the area, which created easy access in the region to Copenhagen and spurred its development as a suburb.

[6] Around 1960, the estates of Gammel Toftegård, Stengård, Stendalsgård, and Kildehom surrounding the old village of Ølstykke were purchased by consortium for residential development.

Ølstykke-Stenløse Amtsgymnasium (now Egedal Gymnasium & HF) began teaching high school students in 1979 out of temporary buildings until a purpose-built structure was completed in 1981.

[3] Since 2000, there has been a second surge in projects, with the development of thousands of new homes and a purpose built municipal center near Egedal Station.

Bus lines offer direct connections from Ølstykke-Stenløse to Holte, Farum, Birkerød, Hillerød, Hundige, Frederikssund, and Roskilde.

10 km to the south-west lies Nationalpark Skjoldungernes Land, the only national part on Zealand, which provides access to Roskilde Fjord.

Egedal municipality's nature strategy places particular emphasis on maintaining the marsh and meadow areas which surround Ølstykke-Stenløse and its other towns.