"I think the way the Bears viewed me as a leader had a great deal to do with it," Clark told ESPNChicago.com on Tuesday. "When you have a guy who can, first off, play football, but also bring some intangible type qualities, that's important. The Bears, since I've been there, have always been the type of organization that looks for the players to police the team. So I think being a leader definitely weighed in their decision.
"But first and foremost, I think that I can come back and contribute to this team."
Clark, who has 242 career receptions with the Bears, including a 45-catch season in 2006, dressed for only five regular-season games in 2010. He had told ESPNChicago.com in January that he did not expect to be back with the Bears in 2011.
"If I had to wager on it, I probably would have said I wouldn't have been back," Clark said. "But after seeing that Greg was traded and Brandon [Manumaleuna] was released, you know I figured there was a possibility I'd come back.
"I feel like there is unfinished business here, so I'm back to try and finish what we started."
Clark joins newly signed Matt Spaeth and veteran Kellen Davis. His role on team is yet to be determined.
Last week the Bears released Manumaleuna, a year after giving him $6 million guaranteed as part of a five-year deal.
Also on Tuesday, the Bears waived safety K.J. Gerard.
Jeff Dickerson covers the Bears for ESPNChicago.com and ESPN 1000.