Allen was drafted by the Minnesota Timberwolves with the fifth pick of the 1996 NBA draft. Immediately after his selection, Allen and Andrew Lang were traded to the Milwaukee Bucks for the rights to fourth pick Stephon Marbury. On July 24, 1996, Allen signed a 3-year, $6.2 million contract with the Bucks. Allen made his NBA debut on November 1, 1996, where he started and played 28 minutes and scored 13 points in a win against fellow rookie Allen Iverson and the Philadelphia 76ers. On January 12, 1997, Allen put in one of his strongest efforts of the season in a win against the Golden State Warriors, contributing 22 points, 6 assists, 3 steals and a new career high of 9 rebounds. In February 1997, Allen competed in the Slam Dunk Contest during All-Star Weekend, where he finished fourth. Continuing his strong rookie season, on March 25, 1997, Allen scored a new career high of 32 points in a loss to the Phoenix Suns. Allen was named to the NBA All-Rookie Second Team.