Minor League players and Major League Baseball have struck a tentative deal on the first collective bargaining agreement between the sides, according to sources.

The pact will more than double player pay.

The agreement, which will last for five years, comes after a rapid and successful effort last year by minor leaguers to unionize under the umbrella of the MLB Players Association and follows previous improvements in housing and pay.

The pay increases at each level are significant, according to sources, and will pay players for most of the offseason as well as spring training, including back pay for this season.