HELENA, Mont. -- The University of Montana Grizzlies will stay in the Big Sky Conference and not move up to the Football Bowl Subdivision, school president Royce Engstrom said Thursday.

"It was a complex decision with many pros and cons," Engstrom said in a statement. "In the end, the better course is to stay with the conference we helped establish in 1963 and to continue building on its solid foundation."

Engstrom said there were three keys to his decision -- he wanted to maintain the cross-state football rivalry with Montana State; he wanted the Grizzlies to compete against institutions with similar academic missions; and he wanted to maintain the prestige and integrity the program has demonstrated.

"At this time, FCS football presents the best overall fit for the University, it provides our student-athletes and fans with a great experience, and it is consistent with the strategic direction of the University," Engstrom said.

Montana athletic director Jim O'Day, Commissioner of Higher Education Sheila Stearns and Board of Regents chairman Clayton Christian all said they agreed with the decision.

Montana will compete in an expanded Big Sky Conference in 2012, as the league recently added Cal Poly, UC Davis, North Dakota and Southern Utah.

The Western Athletic Conference had put Montana high on its list as it looked for new members. But WAC commissioner Karl Benson had said the conference was waiting for Montana to decide what it wanted to do before issuing an invitation.