The LIU Post Pioneers were the athletic teams that represented the C.W. Post Campus of Long Island University, located in Brookville, New York, in NCAA Division II intercollegiate sports through the 2018–19 school year. The Pioneers most recently competed as members of the East Coast Conference for most sports; the football team was an affiliate of the Northeast-10 Conference. LIU Post had been a member of the ECC since 1989, when the league was established as the New York Collegiate Athletic Conference. The LIU Post Pioneers passed into history after the 2018–19 school year when LIU merged the Pioneers with the LIU Brooklyn Blackbirds, the Division I program of the school's Brooklyn campus. The current LIU program now competes as the LIU Sharks, with the new nickname having been selected by polling of alumni and students of the two campuses. Since LIU Brooklyn was a long-established Division I program, the Division II LIU Post teams for sports that had not been sponsored by LIU Brooklyn immediately moved to Division I without the usual transition period for an institution moving to a different division. Teams for sports sponsored by both campuses were merged, and D-II athletes unable to make the D-I teams were allowed to either continue their athletic scholarships without competing or to be granted waivers that allowed them to transfer to another D-II school without having to sit out a season. The LIU Sharks inherited the Northeast Conference membership of the Brooklyn campus.
In baseball, future Major League Baseball outfielder Richie Scheinblum batted.415 in 1964, and set the C.W. Post records in career triples and batting average. He was inducted in the college's sports Hall of Fame in 2005.
Lacrosse
LIU Post won three NCAA Division II Men's Lacrosse Championships. Their first title came in 1996 when they defeated Adelphi 15–10 in the championship and their second came in 2009 when they defeated Le Moyne 8–7 at Gillette Stadium in Foxborough, Mass. The third title came in 2010 when they defeated Le Moyne 14–9 in a rematch of the 2009 title game at M&T Bank Stadium in Baltimore. The LIU Post women's lacrosse team had a perfect, undefeated season and won the NCAA Division II Women's Lacrosse Championship in 2007.