Follo is one of three traditional and judicional districts in the fylke (county) of Akershus, Norway, the other two being Romerike and Asker og Bærum. Follo borders Oslo to the North-West, fellow Akershus district Romerike to the North-East and East, and Østfold to the south.
The municipalities of Frogn and Vestby have coastlines along the Oslofjord. Ås and Oppegård have coastlines along the Bunnefjord (a part of the Oslofjord that extends south-east), and Nesodden has coastlines along both fjords.
In the displayed map of Akershus, the municipalities are numbered. Follo consists of: Nesodden (13), Frogn (7), Vestby (21), Oppegård (15), Ås (22), Ski (18), and Enebakk (5). Follo covers around 819 km², and had a population of 121 368 on October 1, 2007.
As with other traditional districts in Norway, Follo has no official political or administrative significance - the regional administrative entity is the fylke, while the local administrative entities are the kommuner (municipalities). It does, however, have judicional significance, as a local police and court district. It also has practical significance, as the municipalities within the district tend to cooperate for practical and economical purposes.
The largest town, and de facto district capital, is Ski. This is where judicial functions such as Follo Tingrett (Follo district court) and Follo Politikammer (Follo Police District) are located, and where the cooperating municipalities tend to concentrate administrative functions and public services.
All municipalities in Follo are within an hour's drive from Oslo, and large parts of the workforce actually work in Oslo. Apart from the long coastline, Follo has extensive woods and farmland, and only little industry. Most parts of Follo are well suited for outdoor activities, and many athletes have come from this district – such as Trine Hattestad (javelin), Jon Rønningen (wrestling), and Siren Sundby (sailing).
The Norse form of the name was Folló (from *Foldló). The first element is the old name of Oslofjord (see Østfold and Vestfold), the last element is ló f 'meadow' (see also Lom and Oslo).
After the local elections in 2015 five of the municipalities (Ski, Ås, Enebakk, Nesodden and Vestby) have a mayor from the Labour Party, while two (Oppegård and Frogn) have a mayor from the Conservative Party