Major League Baseball rosters

August 1905 photo of players on the Pittsburgh Pirates' roster.

A Major League Baseball roster is a list of players who are allowed, by league agreement, to play for a Major League Baseball (MLB) team. Each MLB team maintains two rosters: an active roster of players eligible to participate in an MLB game, and an expanded roster encompassing the active roster plus additional reserve players.

Beginning with the 2021 season, the active roster size is 26 players, and the expanded roster size is 40 players (the expanded roster is commonly referred to as the "40-man roster"). Historically, the active roster size was 25 players, with exceptions made in some seasons, most recently in 2020 when teams could have 28 active players.