on july 3, 2013, stevens was signed as the head coach for the boston celtics to coach in the nba. in april 2015, in his second season as head coach, stevens led the celtics to the 2015 playoffs as the seventh seed in the eastern conference with a 40–42 record. on april 21, 2015, it was announced that stevens finished fourth in voting for the nba's coach of the year award. in april 2016, stevens led the celtics to their second consecutive playoff appearance as the fifth seed in the 2016 playoffs, finishing the season with a 48–34 record.