INDIANAPOLIS — The first step toward an aristocracy in college sports was codified Thursday, when the five richest conferences and their 65 universities were awarded the right by the Division I board of directors to make their own rules on several issues affecting athletes and competition.

If the endorsement passes a 60-day comment period, the so-called Big 5 — the Southeastern Conference, the Atlantic Coast Conference, the Pacific-12, the Big Ten and the Big 12 — will receive the power to raise the value of scholarships, improve health insurance, allow players to consult agents and more.

“It keeps Division I together in terms of our ideals for amateur sports,” said Nathan Hatch, the president of Wake Forest, who led the steering committee that conceived the proposal. “This is not complete autonomy.”

The result of the vote seemed to acknowledge that even within the nearly 350 institutions in the N.C.A.A.’s top division, universities and conferences are in markedly different situations.