Dorset & Wilts 1 South is an English Rugby Union league, forming part of the South West Division, for clubs primarily based in Dorset, sitting at tier 8 of the English rugby union system. Originally a single league, Dorset & Wilts 1 split into north and south regional divisions in 2004. Teams based in Berkshire participated until 2001 when they left to join the Buckinghamshire & Oxon leagues.
Promoted teams tend to move up to Southern Counties South, while relegated generally teams drop to Dorset & Wilts 2 South. Only 1st XV sides can be promoted into Southern Counties South, while any side can fall to Dorset & Wilts 2 South. Each year all 1st XV sides in the division also take part in the RFU Senior Vase – a level 8 national competition – provided they are members of the Dorset & Wilts RFU.
2021–22
Dorset Dockers (2nd in 2019-20) and East Dorset (11th in Dorset & Wilts 2 South in 2019-20) merged to form East Dorset Dockers for season 2021-22.
The 2015–16 Dorset & Wilts 1 South consisted of twelve teams; nine based in Dorset, two in south Wiltshire and one from Somerset. The season started on 12 September 2015 and ended on 23 April 2016.
The cancellation of National League 5 South at the end of the 1995–96 season meant that Berks/Dorset/Wilts 1 reverted to being a tier 8 league. Further restructuring meant that promotion was now to Southern Counties South[f], while relegation continued to Berks/Dorset/Wilts 2.
Ahead of the 2004–05 season, local league restructuring saw Dorset & Wilts 1 split into two tier 8 regional divisions: Dorset & Wilts 1 North and Dorset & Wilts 1 South. Promotion continued to Southern Counties South, while relegation was now to Dorset & Wilts 2 South.
Despite widespread restructuring by the RFU at the end of the 2008–09 season, Dorset & Wilts 1 South remained a tier 8 league, with promotion continuing to Southern Counties South and relegation to Dorset & Wilts 2 South.
^No relegation due to league expansion from 8 teams to 10.
^No relegation due to league restructure the following season as the league would split into 2 regional leagues - Dorset & Wilts 1 North and Dorset & Wilts 1 South.
^No relegation as division restructured from 9 to 11 teams for the next season.
^Not promoted as Swanage & Wareham 1st team in league above.
^Not promoted as Wimborne 1st team in league above.
^Swanage & Wareham II were relegated despite finishing 7th due to the Swanage & Wareham 1st XV being relegated from Southern Counties South for the following season.
^Reduced from 12 to 11 teams after North Dorset II withdrew from league.
^One of Blandford's titles was won when league was known as Berks/Dorset/Wilts 1.
^One of Dorchester's titles was won when league was known as Berks/Dorset/Wilts 1.
^Dorcester have won four titles overall - three by the 1st team and one by the 2nd team.
^One of Ivel Barbarians titles was won when league was known as Berks/Dorset/Wilts 1. Ivel Barbarians are now known as Yeovil Rugby Club.
^Both of Bracknell's titles were won when league was known as Berks/Dorset/Wilts 1.
^One of Sherborne's title was when the league was known as Berks/Dorset/Wilts 1, the other when league was known as Dorset & Wilts 1.
^One of Swanage & Wareham's titles was won when league was known as Berks/Dorset/Wilts 1.
^Swanage & Wareham have won three titles overall - two by the 1st team and one by the 2nd team.
^Both of Swindon's titles was won when league was known as Berks/Dorset/Wilts 1.
^One of Weymouth & Portland's titles was won when league was known as Berks/Dorset/Wilts 1.
^Devizes title was won when the league was known as Berks/Dorset/Wilts 1.
^Frome's title was won when league was known as Dorset & Wilts 1.
^Royal Wootton Bassett's title was won when league was known as Berks/Dorset/Wilts 1.
^Swindon's title was won when league was known as Berks/Dorset/Wilts 1.
^Trowbridge's title was won when league was known as Berks/Dorset/Wilts 1.
^Westbury's title was won when league was known as Dorset & Wilts 1.