Each team in men’s field lacrosse has ten players on the field. The standard lineup consists of one goalkeeper, three defensemen, three midfielders, and three attackmen.
The positions divide the field into complementary responsibilities. The goalkeeper protects the net, defensemen guard the team’s defensive end, attackmen usually operate near the opposing goal, and midfielders transition between offense and defense. Midfielders often cover the greatest distance because they must support both ends of the field.
Men’s lacrosse is frequently confused with box lacrosse, an indoor version generally played with six players per team on the floor, including a goaltender. Women’s field lacrosse also uses a different number of players under its modern rules, so the question’s reference to men’s lacrosse is important.
Teams may substitute players during play, commonly through the substitution box near midfield. Faceoffs begin quarters and follow goals, and players can leave or enter while the game continues. Despite those substitutions, the on-field team remains limited to ten players, provided the team is not serving a penalty that creates a man-down situation.