Unless rain interferes, one of the largest football rallies in recent years will take place tonight in front of the IAB. In addition to the Harvard cheerleaders and band, the Princeton band is also expected to serenade the crowd.

With the rally crowd forecast at near-riot size, Matthew J. Toohey, the chief of the University police, has ordered 20 more men to be on hand to prevent a disturbance. He was confident yesterday, however, that "everything will be all right."

The parade to the IAB will start at 7 p.m., at the Union, and will proceed down Plympton and Mill Sts. to Holyoke St. At the IAB, Coach Lloyd Jordan will give a short talk, and introduce Captain Bill Meigs.

In Princeton yesterday, Lloyd Kurtz, manager of the Tiger band, said one bus load of musicians was leaving at 1:15 p.m., in time to reach Cambridge by early evening. "I can't promise you that we'll serenade," Kurtz said, "but we'll sure try to. At first we wanted to do it at 6 a.m., but that was too early. There is a good chance, however, that we'll try something at night."

While the rally is taking place, a more dignified discussion will be held in Emerson D. At 7 p.m., Robert H. King '57 and James L. Kincaid '58 will debate a pair of Princetonians on the subject: "Resolved, "Wellesley prefers Harvard to Princeton." Five Wellesley girls will be the judges.

Police at Princeton said yesterday that they were sending two men from their force here to supervise at an Orange Key Dance Saturday night in the Hotel Commander.