(French: “the crosier”), competitive sport, modern version of the North American Indian game of baggataway, in which two teams of players use long-handled, racketlike implements (crosses) to catch, carry, or throw a ball down the field or into the opponents' goal. The goal is defined by uprights and a crossbar framing a loose net.

The distinctive feature of the game is the crosse, the implement used by the players to carry, catch, and pass the ball. The crosse is a staff of wood, usually hickory, the top being sharply bent to form a hook from the end of which a thong is drawn and fastened to the shaft about 2 or 3 feet (0.6 or 0.9 m) from the end of the handle, forming an oval triangle that is woven with a loose network of leather, nylon, or gut to form the pocket with which the ball is handled.

Lacrosse was played by the Six Nations of the Iroquois in what became upper New York state and lower Ontario long before Christopher Columbus landed in the New World. The sport was then much rougher than it is today. Among some tribes as many as a thousand players took part on each side, goals were miles apart, and a game could last as long as three days. Each player tried to disable as many opponents as possible with the stick he carried and afterward concentrate on scoring a goal. The Cherokee called their version of the game “little brother of war.” Because of the endurance required and the injuries that had to be borne with fortitude it was considered excellent training for combat. Among many tribes the game was as much a mystic ceremony as a sport and was preceded by complex rituals and a solemn dance. In some areas men and women played together, and in other areas women had their own version of the game. Indians on government reservations in the United States and Canada still field strong teams.

To the first French settlers in Canada who saw the game, called baggataway, or tewaraathon, by the Indians, the shape of the implement used to catch, carry, and throw the ball suggested a bishop's crozier (la crosse), giving the sport its name.

Europeans in Canada started playing the game about 1840, and the first lacrosse organization, the Olympic Club, was founded in Montreal in 1842. In playing Indian teams, white players lost so frequently they were allowed to field extra men. Members of the Montreal Lacrosse Club (founded 1856) modified the rules somewhat, and in 1867 George Beers of Montreal, called “the father of lacrosse,” made further changes that included replacing the Indian ball of deerskin stuffed with hair by a hard rubber ball, limiting the number of players on a team to 12, and improving the stick for easier catching and throwing of the ball. The 12 players were designated at that time as goal, point, cover point, first defense, second defense, third defense, centre, third attack, second attack, first attack, out home, and in home. In 1867 the National Lacrosse Association was formed, and the game was introduced to England. Captain W.B. Johnson of Montreal toured with a team of Caughnawaga Indians, appearing at Windsor Castle before Queen Victoria, who found the game “very pretty to watch.” The English took to the sport and the game achieved popularity, notably in Lancashire, Cheshire, Yorkshire, Manchester, Bristol, and London. The English Lacrosse Union was founded in 1892, and the All-England Women's Lacrosse Association was formed in 1912. English teams exchanged visits with teams from the United States and Canada from time to time, and combined Oxford-Cambridge teams frequently exchanged visits with college or all-star teams from the United States. The game was also introduced in Ireland, Australia, and South Africa.

In the United States, a team of Indians introduced lacrosse at Troy, N.Y., about 1868, and a few years later teams were started in that city, New York City, and Brooklyn. In the 1880s Eastern schools including New York University, Princeton, Yale, and Harvard took up the sport. In 1884 a successful tour of Europe was made by a team of U.S. collegians, and in 1906 the U.S. Intercollegiate Lacrosse League was formed. The game received its greatest impetus, however, when it was introduced to Baltimore by some track-and-field athletes, who had seen the game played by Canadians on Long Island. The Baltimoreans actively promoted the sport, aiming at all age levels, so that Baltimore became the main U.S. centre of lacrosse. During the 1920s women field hockey players discovered lacrosse, and in 1931 the U.S. Women's Lacrosse Association was formed.

The Intercollegiate Lacrosse League was reorganized in 1926 as the U.S. Intercollegiate Lacrosse Association, which had about 120 member colleges. In 1970 the National Collegiate Athletic Association (NCAA), with more than 500 member colleges, undertook sponsorship of intercollegiate lacrosse competition, reflecting the growth of the sport in the country outside its traditional Eastern Seaboard stronghold. NCAA national championship tournaments for men began in 1971; women's tournaments began in 1982. The college team considered the best in the country is awarded the Wingate Trophy.

Lacrosse was included in the Olympic Games in 1904 and 1908 with teams representing Canada, the United States, and Great Britain. Teams from those countries also demonstrated the sport in exhibitions at the Games in 1928, 1932, and 1948, but it did not attract enough international interest to remain an Olympic sport. World Championships for men have been held since 1967. Women's World Championships were held from 1969 to 1982, when they were replaced by the World Cup. A variant of lacrosse, called box lacrosse (q.v.), was introduced in Canada in 1930.

The field is 110 yards (about 100 m) long and 60 yards wide. The goals are 80 yards apart, the goal posts being 6 feet (1.8 m) high and the same distance apart, surmounted by a crossbar. The posts are fitted with a netting fastened to the ground behind the goal to stop passage of the ball after a successful shot. The goal-area lines, wing lines, and centre line act as restraints on the movements of certain players during play. Passing over a line into a prohibited area results in a penalty.

The ball is of sponge rubber, not less than 7.75 to 8 inches (19.7 to 20.3 cm) in circumference, and is from 5 to 5.25 ounces (142 to 149 g) in weight.

The width of the crosse at the top, or head, may not be more than 12 inches nor is it to be less than 7 inches. The length of the stick may not be more than 6 feet nor less than 3 feet, with the exception being the goalkeeper's stick, which may be of any length. Shoes have rubber, plastic, or metal cleats. Each player wears a helmet with a face mask or guard. Leather gloves protect the hands and wrists. Light pads are worn under the jersey to protect the shoulders and arms. The goalkeeper wears, in addition, a chest protector.

Lacrosse is a very fast game, the object of which is to send the ball through the opponents' goal as many times as possible and to prevent one's opponents from scoring. A goal counts one point. Men's teams usually have 10 players: the goalkeeper, three defensemen, three midfielders (one of whom is the centre), and three attackmen. During play each team must have at least four players in its defensive half of the field and no fewer than three in its offensive half of the field. This rule prevents excessive crowding around a goal when it is under attack. Conventionally, the goalkeeper and the three defensemen stay in the defensive half, while the three attackmen stay in the offensive half. The midfielders are permitted to roam the field, reinforcing the attack or defense as needed. There are two officials, a referee and a judge.

The game is divided into four periods of 15 minutes each, with intervals of one minute between the first and second quarters and between the third and fourth quarters and a 10-minute rest at halftime. If the score is tied at the end of regulation time, play is resumed after an intermission of five minutes for two four-minute periods, with a one-minute rest in between. Free substitution is allowed.

A player may run with the ball, pass it in any direction, and catch it, but—with the exception of the goalkeeper—he may not touch it with his hand. A player may kick the ball or bat it, but not into the opponents' goal. A unique feature of the game is “cradling,” in which the player rapidly rotates the stick in half-turns while holding it nearly upright as he runs. The centrifugal force developed keeps the ball in the pocket of the crosse and also puts it in position for accurate throwing. Defensive players are allowed to poke the ballcarrier in the body with their sticks or slap at his stick to dislodge the ball. Blocking the ballcarrier—i.e., hitting him with the shoulder in an attempt to throw him off-balance or knock him down—is legal. For minor infractions of the rules the penalty is either suspension from the game for 30 seconds or an exchange of the ball. In the case of personal fouls of a more serious nature—for example, an illegal block—the offender is suspended from the game for one, two, or three minutes, and his team plays a man short for that period of time. Other serious fouls include tripping, slashing, and unnecessary roughness.

Play is started at the beginning of each quarter and after the scoring of a goal with a face-off at midfield, as in hockey. The two centres face each other, the heads of their sticks touching the ground. The referee places the ball between the two crosses and at his signal each player tries to gain control of the ball. He may keep it himself or bat it to a teammate. The player with the ball tries to advance it toward the opposing goal by running or passing to a teammate in the open. The defenders try to harry him into making a poor pass, intercept the ball when it is thrown, knock the ball from his stick, or occasionally knock it loose with a block. Players are in constant movement: dodging, hurling, or flipping the ball to a teammate; scooping up the ball while running at full speed; or making quick, deceptive shots at the goal. A unique ceremony at the beginning of the game consists of the teams lining up in the centre of the field opposite each other. Each player introduces himself to his particular opponent, shakes hands, and wishes him luck.

Popular in the British Isles, Australia, Canada, New Zealand, South Africa, Switzerland, and the United States, women's lacrosse was first played in Scottish and English private schools in the early 1900s and was introduced to schools and colleges in the eastern United States by English women teachers. Frequent exchange visits by American and English women's teams followed, the latter showing themselves to be the best in the world. Britain-Ireland touring teams have excellent records against American teams.

The women's game allows no body contact or rough play with the stick. The goalkeeper wears a chest pad and leg guards. There are 12 players on a side. The goals are 90 to 110 yards apart, and there are no sidelines or end lines, the goal creases and centre circle being the only ground markings. A game consists of 25-minute halves, with a 10-minute intermission. There is no overtime in the case of a tie. The rules established by the All-England Ladies' Lacrosse Association are universally accepted by other nations. In the United States, the Philadelphia, Baltimore, and Boston areas furnish strong teams, while the main English centres of women's lacrosse are Hertfordshire, Kent, Norfolk, Essex, and Suffolk.