The population was 1,256 at the 2011 census
Nearby villages are Penygroes, Carmel and Dinas. The village lies approximately five miles south of Caernarfon. It has one primary school in the centre of the village and no secondary schools. Most secondary school age pupils go to Ysgol Dyffryn Nantlle in Penygroes.
Formerly an agricultural and slate mining village, Groeslon is now expanding as a commuter village for the surrounding towns, especially Caernarfon and Bangor. Its initial growth came as a result of the construction of the LMS railway in 1867. Groeslon railway station closed in December 1964. The railway line is now part of the national cycle route.
In the village there is one pub called the Penionyn.
At the bottom of the village, bordering the A487, a huge wall becomes visible. This is the wall to the Glynllifon estate, formerly the seat of Lord Newborough, which is now a country park and college (Meirion Dwyfor) specialising in land based industries, e.g. agriculture, equine studies and arboriculture.
Groeslon is covered by a Neighbourhood Policing Team based in Penygroes.
- Welsh author Eirug Wyn until his death in 2004.
- The dramatist John Gwilym Jones (1904–1988)
- Poet Tom Huws.
- Llion Iwan, Welsh documentary journalist/producer and author.
- 'The Laughing Postman' Arwel Jones.
- Novelist Menna Medi
Hanes Y Groeslon (History of Groeslon) available from public libraries: 
- "Ward population 2011". Retrieved 15 May 2015.
- Dyffryn Nantlle website (with section on Groeslon, including postcards and photos)
- www.geograph.co.uk : photos of Groeslon and surrounding area
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