Ivy League Group Agreement to all intercollegiate sports, effective with the 1955–56 basketball season. This is generally reckoned as the formal formation of the Ivy League. As part of the transition, Brown, the only Ivy that hadn't joined the EIBL, did so for the 1954–55 season. A year later, the Ivy League absorbed the EIBL. The Ivy League claims the EIBL's history as its own. Through the EIBL, it is the oldest basketball conference in Division I. As late as the 1960s many of the Ivy League universities' undergraduate programs remained open only to men, with Cornell the only one to have
Ivy League games. In only 11 instances in the history of Ivy League basketball, and in only seven seasons since Yale's 1962 title, has neither Penn nor Princeton won at least a share of the Ivy League title in basketball, with Princeton champion or co-champion 26 times and Penn 25 times. Penn has won 21 outright, Princeton 19 outright. Princeton has been a co-champion 7 times, sharing 4 of those titles with Penn (these 4 seasons represent the only times Penn has been co-champion). Harvard won its first title of either variety in 2011, losing a dramatic play-off game to Princeton for