Base-Ball (so-called from the bases and ball used), the national summer sport of the United States, popular also throughout Canada and in Japan. Its origin is obscure. According to some authorities it is derived from the old English game of rounders (q.v.), several variations of which were played in America during the colonial period; according to other authorities, its resemblance to rounders is merely a coincidence, and it had its origin in the United States, probably at Cooperstown, New York, in 1839, when it is said, Abner Doubleday (later a general in the U.S. army) devised a scheme for playing it. About the beginning of the 19th century a game generally known as "One Old Cat" became popular with schoolboys in the North Atlantic states; this game was played by three boys, each fielding and batting in turn, a run being scored by the batsman running to a single base and back without being put out. Two Old Cat, Three Old Cat, and Four Old Cat were modifications of this game, having respectively four, six, and eight players.

A development of this game bore the name of town-ball and the Olympic Town-Ball Club of Philadelphia was organized in 1833. Matches between organized base-ball clubs were first played in the neighbourhood of New York, where the Washington Baseball Club was founded in 1843. The first regular code of rules was drawn up in 1845 by the Knickerbocker Baseball Club and used in its matches with the Gotham Eagle and Empire clubs of New York, and the Excelsior, Putnam, Atlantic and Eckford clubs of Brooklyn. In 1858 the first National Association was organized, and, while its few simple laws were generally similar to the corresponding rules of the present code, the ball was larger and "livelier," and the pitcher was compelled to deliver it with a full toss, no approach to a throw being allowed. The popularity of the game spread rapidly, resulting in the organization of many famous clubs, such as the Beacon and Lowell of Boston, the Red Stockings of Cincinnati, the Forest City of Cleveland and the Maple Leaf of Guelph, but owing to the sharp rivalry between the foremost teams, semi-professionalism soon crept in, although in those days a man who played for a financial consideration always had some other means of livelihood, as the income to be derived from playing ball in the summer time was not enough to support him throughout the year.

In spite of its popularity, the game acquired certain undesirable adjuncts. The betting and pool selling evils became prominent, and before long the game was in thorough disrepute. It was not only generally believed that the matches were not played on their merits, but it was known that players themselves were not above selling contests. At that time many of the journals of the day foretold the speedy downfall of the sport. A convention of those interested financially and otherwise in the game, was held in 1867 in Philadelphia, and an effort was made to effect a reformation. That the sport even then was by no means insignificant can be seen from the fact that in that convention some 500 organizations were represented. While the work done at the convention did not accomplish all that was expected, it did produce certain reforms, and the sport grew rapidly thereafter both in the eastern and in the middle western part of the United States. In the next five years the interest in the game became so great that it was decided to send a representation of American base-ball players to England; and two clubs, the Bostons, who were the champions that year, and the Athletics, former champions, crossed the Atlantic and played several exhibition games with each other.

While successful in exciting some interest, the trip did not succeed in popularizing base-ball in Great Britain. Fifteen years later two other nines of representative American base-ball players made a general tour of Australia and various other countries, completing their trip by a contest in England. This too, however, had little effect, and later attempts to establish base-ball in England have likewise been unsuccessful. But in America the game continued to prosper. The first entirely professional club was the Cincinnati Red Stockings (1868). Two national associations were formed in 1871, one having jurisdiction over professional clubs and the other over amateurs. In 1876 was formed the National League, of eight clubs under the presidency of Nicholas E. Young, which contained the expert ball-players of the country. There were so many people in the United States who wanted to see professional base-ball that this organization proved too small to furnish the desired number of games, and hence in 1882 the American Association was formed. For a time it seemed that there would be room for both organizations; but there was considerable rivalry, and it was not until an agreement was made between the two organizations that they were able to work together in harmony.

They practically controlled professional base-ball for many years, although there were occasional attempts to overthrow their authority, the most notable being the formation in 1890 of a brotherhood of players called the Players' League, organized for the purpose of securing some of the financial benefits accruing to the managers, as well as for the purpose of abolishing black-listing and other supposed abuses. The Players' League proved not sufficiently strong for the task, and fell to pieces. For some years the National League consisted of twelve clubs organized as stock companies, representing cities as far apart as Boston and St Louis, but in 1900 the number was reduced to eight, namely, Boston, Brooklyn, Chicago, Cincinnati, New York, Pittsburg, Philadelphia and St Louis. Certain aggressive and dissatisfied elements took advantage of this change to organize a second great professional association under the presidency of B. B. Johnson, the "American League," of eight clubs, six of them in cities where the National League was already represented.

Most of the clubs of both leagues flourish financially, as also do the many minor associations which control the clubs of the different sections of the country, among which are the Eastern League, the American Association, Western League, Southern Association, New England League, Pacific League and the different state leagues. Professional base-ball has not been free from certain objectionable elements, of which the unnecessary and rowdyish fault-finding with the umpires has been the most evident, but the authorities of the different leagues have lately succeeded, by strenuous legislation, in abating these. Of authorities on base-ball, Henry Chadwick (d. 1908) is the best known.

Amateur base-ball, in its organized phase, is played mostly by school and university clubs as well as those of athletic associations. The first college league was formed in 1879 and comprised Harvard, Princeton, Amherst, Brown and Dartmouth, Yale joining a year later. The Eastern College League, with Columbia, Harvard, Princeton and Yale, followed in 1887. This was afterwards dissolved and at present the most important universities of the eastern states are members of no league, although such organizations exist in New England and different parts of the west and south. Amateur base-ball has progressed along the same lines as professional, although the college playing rules formerly differed in certain minor points from those of the professional leagues.

The following is a general description of the field and of the manner in which the game is played, but as the game has become highly complicated, situations may arise in playing in which general statements do not strictly hold. Any smooth, level field about 150 yds. long and 100 yds. broad will serve for a base-ball ground. Upon this field is marked out with white chalk a square, commonly called the diamond, smooth, like a cricket pitch, the sides of which measure 30 yds. each, and the nearest corner of which is distant about 30 yds. from the limit of the field. This corner is marked with a white plate, called the home-base or plate, five-sided in shape, two of the sides being 1 ft. long and that towards the pitcher 17 in. At the other three corners and attached to pegs are white canvas bags 15 in. square filled with some soft material, and called, beginning at the right as one looks towards the field, first-base, second-base and third-base respectively. The lines from home-base to first, and from home to third are indefinitely prolonged and called foul-lines. The game is played by two sides of nine men each, one of these taking its turn at the bat while the other is in the field endeavouring, as provided by certain rules, to put out the side at bat.

Each side has nine turns, or innings, at bat, unless the side last at bat does not need its ninth innings in order to win; a tie at the end of the ninth innings makes additional innings necessary. A full game usually takes from 1½ to 2 hrs. to play. Three batsmen are put out in each innings, and the side scoring the greatest number of runs (complete encircling of the bases without being put out) wins. A runner who is not put out but fails to reach home-base does not score a run, but is "left on base."