From 1978 to June 1980, Greenberg was an assistant coach at Columbia University under Buddy Mahar. Greenberg later joined Roy Chipman as an assistant coach at the University of Pittsburgh from 1980 to 1983. In that era, Pittsburgh appeared in the NCAA Tournaments of 1981 and 1982. For the 1983–84 season, Greenberg was an assistant on Terry Holland's Virginia team that made the Final Four of the 1984 NCAA Tournament. Greenberg later worked as an assistant under Bill Foster at the University of Miami from 1985 to 1987.
In 1987, Greenberg became associate head coach at Long Beach State under Joe Harrington. Long Beach State appeared in the National Invitation Tournaments of 1988 and 1990.
Long Beach State head coach (1990–96)
Long Beach State promoted Greenberg to head coach in 1990. In six seasons with Greenberg as head coach, Long Beach State went 105–70, second behind Jerry Tarkanian for the most wins in the program's history. Postseason appearances during the Greenberg era included the 1992 NIT, 1993 NCAA Tournament, and 1995 NCAA Tournament. In the 1992–93 season, Long Beach State also had its first Top 25 ranking in 14 years. On January 25, 1993, Long Beach State upset #1 Kansas 64-49 at Allen Fieldhouse. Long Beach State won the Big West Tournament in 1993 and 1995. While at Long Beach, Greenberg was a mentor of two successful future NBA players, Lucious Harris and Bryon Russell.
Greenberg was head coach at the University of South Florida from 1996 to 2003 and had a 108–100 record there. South Florida became the Conference USA regular season champions in the 1999–00 season and made the NIT after the season. South Florida also made the 2002 NIT.
Virginia Tech (2003–12)
In nine seasons at Virginia Tech, Greenberg attained a 170–123 record. Greenberg's tenure at Virginia Tech began with the school's final season in the Big East Conference before joining the Atlantic Coast Conference in 2004. Following his second season at Virginia Tech that included an appearance in the 2005 NIT, Greenberg won the ACC Coach of the Year award. In 2005, he helped donate 2,400 student tickets to the NIT game against Temple. In 2008, he increased the donations to 3000 tickets for students in all three NIT games played in Cassell Coliseum. During the 2006–07 season, Greenberg led the Hokies to a 22–12 record with signature victories against #5 Dukeon the road and #1 North Carolina at home in an eight-day span. The victories landed the Hokies in the AP Top 25for the first time in over a decade, and earned their first NCAA Tournament appearance since 1996. They received a #5 seed in the West bracket, but fell to Southern Illinois in the second round. Again in 2007–08, Virginia Tech had over 20 wins. Virginia Tech also made the quarterfinals of the 2008 NIT. Greenberg earned his second ACC Coach of the Year award. On January 21, 2009 the Hokies defeated #1 Wake Forest, 78–71. Wake Forest was the only remaining undefeated team in the nation at the time. Virginia Tech made each NIT from 2009 to 2011 and had its most successful season under Greenberg in 2009–10 with a 25–9 record. On February 27, 2011 the Hokies defeated #1 Duke in Cassell Coliseum. Greenberg's tenure as Virginia Tech's head coach ended in April 2012, when Athletic Director Jim Weaver fired him at a surprise news conference. Greenberg was "completely blindsided and shocked" by Weaver's decision. Greenberg was replaced by his former assistant, James Johnson. Greenberg is Jewish, and volunteered to coach the USA Men's Basketball team at the 19th Maccabiah Games in Israel in July 2013.
