A potential flood of underclassmen might crash down on the NBA draft camp in Chicago after the NCAA Board of Governors approved new legislation Thursday offering a penalty-free, NBA-sponsored all-expenses paid trip there in early June.

Those who are undecided about entering the draft -- Saint Joseph junior point guard Jameer Nelson, Syracuse sophomore forward Hakim Warrick, Alabama sophomore point Mo Williams, Notre Dame sophomore point Chris Thomas -- might declare now because attending the camp would come at no cost and test their draft status without the loss of eligibility.

The Board of Governors unanimously approved the legislation in Indianapolis after it was unanimously approved by the NCAA's management council last week.

The legislation allows college underclassmen to attend the NBA draft camp without having to reimburse the NBA for expenses. The underclassmen are allowed to play in the three games at the draft camp June 3-6 at Moody Bible Institute in Chicago without having to sit out a game-for-game penalty if they return to school.

"If we let kids put their name in the draft, then we need to allow them to realistically test themselves against competition," said Steve Mallonee, the NCAA's director of legislative services.

Underclassmen have until May 12 to declare for the June 26 draft. They still cannot sign with an agent and return to college and have until June 19 to withdraw from the draft. If they do not withdraw and go undrafted, they can still return to college if they apply for reinstatement within 30 days of the draft. UC Irvine's Jerry Green did just that two years ago after he went undrafted.

A different set of rules apply to a high school senior. While he can get drafted and go to college, the team that drafts him holds his rights until his eligibility expires. Junior college athletes are ineligible to play for a Division I school if they declare for the draft. All players can go through the draft only once.

For years the NCAA did not enforce a rule on its books that stated if a player who participated in the Chicago draft camp returned to college, then he had to sit a game-for-game penalty. This is why Arizona's Jason Gardner and Kentucky's Keith Bogans were able to participate in the camp in 2001 and still return to college for their junior seasons without having to sit out games.

But the NCAA decided to enforce the rule last June. As a result, underclassmen who were not sure about declaring for the draft stayed away from the camp. Stanford's Casey Jacobsen decided against going to Chicago for fear of sitting out regular-season games if he decided to return for his senior season. Memphis' Chris Massie was the only player who went to Chicago last summer and returned to college. He played in two camp games and was forced to miss two regular-season games after he became eligible. Massie sat out all games in the first semester of school because he was academically ineligible.

Under the old rule, players still had to reimburse the NBA for all expenses.

"A number of guys were hesitant because they didn't want to lose games," one NBA assistant general manager said. "Now these guys have a chance to play in Chicago for free? You're going to have a lot of guys do this."

The board's endorsement of the legislation diminishes the importance of agents early in the draft process, because underclassmen will not want to jeopardize their amateur status. Free trip to Chicago? Players won't need agents for that; they can get their own true reading on their draft status without making themselves ineligible. In the past, underclassmen were scared to test the process because they would have to pay to go to Chicago and then, as was the case last season, may have been forced to sit out games.

"This will make the Chicago draft camp really competitive and could affect the seniors who skipped" the seniors-only Portsmouth (Va.) Invitational earlier this month, said one assistant general manager who helps run the event. Gardner could fall into this group. If point guards like Thomas and Nelson show up in Chicago, Gardner would face much more heady competition that could hurt his draft status even if Thomas and Nelson withdrew before the draft.

The NBA is expected to invite a number of European players to Chicago, as well. A total of 65 players usually are invited to the camp.

The new legislation will not affect the rule governing individual workouts. Underclassmen who attend workouts at a team's facility would still have to pay their own way or reimburse the team if they returned to college. These workouts must take place after the second semester ends.

Andy Katz is a senior writer at ESPN.com.