Ås is a municipality in Akershus county, Norway. It is part of the Follo traditional region. The administrative centre of the municipality is the village of Ås. The parish of Aas was established as a municipality on 1 January 1838 (see formannskapsdistrikt).Ås is one of the fastest growing municipalities in Akershus, with a population of 16.386 in 2009, and a growth of 539 in 2008. Ås is the largest agricultural municipality of Akershus, and home to the Norwegian University of Life Sciences and the amusement park Tusenfryd.
The parish was named after the old Ås farm (Old Norse: Áss), since the first church was built there. The name is identical with the word áss meaning "mountain ridge". Prior to 1921, the name was spelled Aas.The coat-of-arms is from modern times. They were granted on 23 July 1982. The three silver diamonds are a symbol for the many archaeological findings in the area. The diamond (rhombus) shape was taken as it resembled many of the axes found in the area (Nøstvet ax). The silver colour resembles the flint, of which the tools were made of. The number of three diamonds was chosen to represent the three parishes in the municipality: Ås, Kroer and Nordby.