In baseball, a number of coaches assist in the smooth functioning of a team. The most prominent is the manager who determines the lineup and decides how to substitute players during the game. Beyond the manager, more than a half dozen coaches may assist the manager in running the team. Baseball is unique in that the manager and coaches all wear numbered uniforms similar to those of the players.

The team is assisted by two on-field coaches when it is at bat. They are stationed near first and third base to signal and direct the runners and batters. These coaches are called the first base coach and third base coach, respectively, and position themselves in designated coach's boxes. The third base coach typically has more responsibility because he must quickly and accurately signal to a baserunner whether he should attempt to score on a batted ball.

In addition, a team may have several other coaches who specialize in certain disciplines. A pitching coach mentors and trains pitchers. A hitting coach works with players to improve their hitting techniques and form. A bullpen coach is similar to a pitching coach but works primarily with relief pitchers in the bullpen. Another coaching position is the catching instructor who advises catchers. The position of bench coach is relatively new in baseball. The bench coach's responsibilities include helping to set up the day's practice and stretching routines before a game. Once the game begins, the bench coach acts mostly like an assistant manager, offering the manager situational advice.

Teams may hire more than one person for any given coaching position based on the team's needs. Teams may also hire people to serve as general coaches or instructors without any specific title who instead may perform any one or more of the duties listed above. Often times coaches will be former players themselves who can teach current players from their own experience.