From the Zeta Beta Tau website:
During the 1980's, every Greek-letter group continued their efforts to stop hazing. Despite ZBT's best efforts, hazing continued and increased in frequency and severity. ZBT concluded that all efforts to reform the institution of pledging had failed; pledging was the problem. This was because pledges were considered second-class citizens, with no rights and no chance to refuse even the most outrageous demands of a Brother, unless he quit the Fraternity. In 1989, in a last-ditch effort to eliminate hazing, ZBT eliminated pledging and all second-class status from the Fraternity. In its place, ZBT established a Brotherhood Program, with minimum standards (Brotherhood Quality Standards), as well as programs of education, bonding, and earning one's Brotherhood status that applied to all Brothers of ZBT.
http://www.zbt.org/ZBT/About.asp
I remember hearing that they only go through the Brotherhood Program for a very short period of time. But, I may be mistaken.