Os is a municipality in Hordaland county, Norway. It is located in the Midhordland region, just south Norway's second-largest city, Bergen. Due to its proximity to Bergen, Os is experiencing strong population growth. The administrative centre (and commercial centre) of Os is the village of Osøyro. It is the largest settlement in the municipality, with over 60% of the municipal residents living here. Other larger villages in Os include Hagavik, Halhjem, Søfteland, Søre Øyane, and Søvik.