The first ever Twestival, or "tweet-up with a social conscience" raised $250,000 for charity: water. Over 200 cities worldwide participated in February.
Organisers are expecting the next event, Twestival Local, to exceed those fundraising efforts and are inviting cities around the world to join in.
Volunteer teams in the UK and cities across the world are coming together to survey their communities, nominate causes, plan events, gather sponsors and raise funds.
As Twestival originated in the UK, British cities have responded to the call for Twestival Local, with events taking place in 18 cities, including Cardiff, Cornwall, London, Inverness, Liverpool and Newcastle.
This year, cities are encouraged to plan their own events and host them between September 10 and 13, instead all of the same day.
Individual cities can also select their own charities.
Events are presently planned for the banks of Loch Ness to the cliff tops in Cornwall, and charities from Birmingham's YMCA, the Isle of Wight's conservation cause Gift To Nature and Childline in London.
Global partners across all countries for Twestival are Amiando, Citrix Online, Blurb and Causecast.