1996 – The first Major League Soccer season.
2012 – March: U.S. Soccer and MLS created PRO.
2012 – March: Peter Walton appointed PRO General Manager.
2012 – October: www.proreferees.com launched.
2013 – The 100th referee since the inception of Major League Soccer in 1996 officiated an MLS game.
2013 – March: First full MLS season with PRO involvement kicked-off.
2013 – April: Inaugural NWSL season started, officiated by affiliated officials from PRO.
2014 – July: PRO joined forces with Match Analysis to improve performances.
2014 – October: Three PRO officials refereed in the inaugural Indian Super League.
2015 – November: Daltonic Films produced behind-the-scenes video with PRO, published by FOX Soccer > click here to watch.
2016 – February: TAG Heuer announced as official timekeeper of PRO.
2016 – March: PRO held first Referee Development Academy.
2016 – July: PRO partnered with TeamXStream to enhance training and development.
2016 – August: MLS approved by The IFAB for Video Assistant Referee testing in United Soccer League.
2016 – August: PRO officials made history with use of video replay technology in USL.
2017 – August: Video Review makes its MLS debut in Week 22
2018 – January: PRO appoint Howard Webb as GM, replacing Peter Walton