2017–18 Boston Celtics season

The 2017–18 Boston Celtics season was the 72nd season of the franchise in the National Basketball Association (NBA). The Celtics originally acquired the number one pick of the NBA draft due to a previous trade involving the Brooklyn Nets, only to then trade it to the Philadelphia 76ers in exchange for two different draft picks. One of the picks would allow Boston to draft forward Jayson Tatum. Later, they acquired Gordon Hayward in free agency on July 7, 2017. They would also acquire 4-time All-Star Kyrie Irving from the Cleveland Cavaliers via trade on August 22, 2017 in exchange for Ante Žižić, Jae Crowder, All-Star point guard Isaiah Thomas, the Brooklyn Nets' unprotected first-round pick in the 2018 NBA draft, and a 2020 second-round pick, originally from the Miami Heat. The Celtics played the first game of the regular season on October 17, 2017, against the Cleveland Cavaliers.

The team retired the number 34 in honor of former small forward Paul Pierce on February 11, 2018, following a game against the Cavaliers.

In the playoffs, the Celtics defeated the 7th-seeded Milwaukee Bucks in the first round in seven games, advancing to the semifinals, where they faced the Philadelphia 76ers, winning in five games, advancing to the conference finals, where they faced the Cleveland Cavaliers in a rematch of last season's Eastern Conference finals, in which the Cavaliers won 4–3. Despite losing both star acquisitions Gordon Hayward and Kyrie Irving before the playoffs began to season-ending injuries, the Celtics would make this series more hard-fought this time (each game ending with no larger than a deficit of 8 points), but lost in seven games to the Cavaliers, losing 79–87 at home in Game 7. It marks the first time since the 1987–88 season that the Celtics made two consecutive Conference finals.