The Union announced Wednesday that they reached agreements with midfielder Pedro Ribeiro and defender Richie Marquez, both of whom were picked during the 2014 MLS SuperDraft.
The team also waived midfielder Matt Kassel, who spent 2013 with the Union.
Ribeiro, 23, was picked 15th overall out of Coastal Carolina University. He was a First-Team All-Big South player from 2011-13 and compiled 31 goals and 26 assists during his four years with the school.
Marquez, 21, was a four-year Southern California Intercollegiate Athletic Conference First-Team player during his collegiate career at the University of Redlands.
Kassel played a total of 90 minutes in five appearances last season with the team.
The Union open the 2014 season Saturday, March 8, on the road versus the Portland Timbers at 10:30 p.m. The Union home opener comes one week later at PPL Park on Saturday, March 15, at 4 p.m. versus the New England Revolution.