Sheffield's Doc/Fest attracts film makers from all over the world and for the past 15 years has been held in November. Organisers have now said it will move to June from 2011.
Festival chairman Steve Hewlett said: "The event is an outstanding UK and international success story. Over the past four years delegate attendance has risen from 500 in 2005, to 1,885 in 2009.
"This move will allow more inventive programming, more public outreach and allow us to improve our offering and enable us to work more effectively with other creative organisations in Sheffield.
"We'll also be announcing a couple of important partnerships with international documentary organisations in the coming weeks."