Kaitlin Olson was a part of the theater troupe the Groundlings.
She began her career in the Groundlings , an improvisational group in Los Angeles , California , and had minor roles in several television series before being cast as Deandra `` Sweet Dee '' Reynolds on the FX black comedy series It 's Always Sunny in Philadelphia in 2005.
The Groundlings are an improvisational and sketch comedy troupe and school based in Los Angeles , California.
