Syracuse University and the University of Pittsburgh, two bedrock members of the Big East Conference, are engaged in talks about joining the Atlantic Coast Conference, according to a person with direct knowledge of the talks.

No one from Pittsburgh, Syracuse or the A.C.C. denied the conversations were taking place. Officials from all three entities declined to comment on the matter.

The person with knowledge of the talks declined to speculate on a timetable or the seriousness of the discussions. But in this delicate time for conferences and their futures, the discussions between the 12-team A.C.C. and two Big East members are significant.

The talks show how the trend toward 16-team super conferences, which has concerned many college athletic officials, appears to be inching closer to reality. If Syracuse and Pittsburgh switch, the move will be difficult for the Big East to overcome.