The 1999–2000 NBA season was the Mavericks' 20th season in the National Basketball Association. This season is especially notable as Mark Cuban purchased the team from Ross Perot Jr. in January 2000. Under Cuban's leadership, the Mavs built a foundation for continued NBA success that eventually led to two Finals appearances (and one championship) in the next decade. During the off-season, the Mavericks re-acquired former center Sean Rooks from the Los Angeles Lakers.