Lewis joins Quins
"Dave is an extremely experienced Premiership operator," said John Kingston, Harlequins Director of Rugby. "He is perfectly suited to the type of game we like to play.
"He is a scrumhalf with excellent skills and is also a very good reader of the game.
"On top of that, he is an extremely personable guy who will fit into, and enhance, the environment that we are looking to build within the squad,"
Born in Manchester, Lewis progressed through the Exeter Chiefs Academy system and joined Gloucester Rugby in 2007.
Spending six years with the Cherry and Whites, he made 88 appearances, before returning to Exeter in 2013. In his four years with the South-West side, he has made 79 appearances.
In January 2014, the former England Under-20 represented England Saxons against the Irish Wolfhounds, at Kingsholm.
27 year-old Lewis added: "I am really excited to be moving to Harlequins and starting a new challenge in my career. I've always enjoyed the atmosphere at The Stoop and the Quins style of play is something I've admired for a long time. I'm looking forward to getting to know the boys and training hard.
"Exeter Chiefs are an excellent club and, thanks to all there, I feel I've progressed immensely, both on and off the field. I have made some brilliant memories that I'll be taking with me and can safely say I know I've made some life-long friends,"
