A major turning point in the development of modern American football occurred in 1874 when Harvard hosted a club from McGill University (Montreal, Canada).  The teams played the first game under the soccer-style rules, but played a second under rugby rules.  Harvard loved the latter game, which allowed them greater physical contact and to carry an oval, leather ball.  In 1875, Harvard defeated Yale in a game integrating facets of rugby into the older soccer sport.  The next year, Harvard, Columbia, Princeton, and Yale founded the Intercollegiate Football Association (IFA), setting a championship game on Thanksgiving Day.  Under association rules, 15-man squads played two 40-minute halves, and could either carry or kick the ball (although it took four "touch-downs" to equal one kicked goal).  Football debuted in the Midwest in 1879, when the University of Michigan played Racine College (Wisconsin).

Walter Camp is often called the "father of American football" for his many contributions to the development of the sport.  As a player (1876-1882), his Yale team dominated the game with a 30-1-5 record.  As a Yale field coach for almost 30 years, and a member of the IFA rules committee (1878-1925), he was responsible for important innovations.  As a coach, he organized practices to include warm-up and stretching exercises, repetitive drills, and hour-long scrimmages, and introduced coded signals, strategies, the quarterback "snap," tackling dummies, and filming scrimmages.  In 1883-1891, Yale applied Camp's methods to outscore their competition 4660 to 92, losing only three games.  On the rules committee, he reduced the size of the playing field (to 110 x 53 yards) and squads (to 11 men); proposed that the team of the downed ball-carrier retain possession (soon limited to three, and later four, "downs"), with play restarting at a line of scrimmage; and revamped the scoring system to emphasize ball carrying instead of kicking.

During the 1880s, football evolved from a primarily participatory game to a spectator sport.  In 1880, the IFA championship game was moved to New York City, where the paid attendance of 5000 (mainly from the urban middle class, not students) grew to 23,000 by 1887 and 40,000 by 1891.  Until the 1890s, football was eclipsed in popularity and profits on college campuses by baseball and crew.  In 1894, concern over post-game riots in the seedy tenderloin district of New York City, and loss of control over the game, influenced the IFA to return the championship game to campus in 1894, despite the lucrative gate-receipts in the Big Apple.  Attendance fell by half in 1895, but climbed over the ensuing years.  During the 1890s, Yale's annual revenue from college football exceeded $50,000.  

In 1892, the University of Chicago lured coach Amos Alonzo Stagg away from Yale, giving him chairmanship of the "physical culture" department and an enormous salary of $6000.  Stagg continued to be the most successful football coach of the era, setting a record 323 wins not broken until 1971 by Alabama's Paul "Bear" Bryant.  Midwestern colleges wanted to assert their independence against the dominant Northeastern schools, and in 1895 formed what would become known as the Big Ten Conference.

In the 1890s, recruitment of top players through scholarships and other inducements became a major part of the college sport, and by the turn of the century, competition was intense.  Once on campus, star players were often treated royally.  In 1904, Yale football captain James Hogan received free room and board, a luxury apartment at the University Club, a profit-share in the baseball gate, a commission from the American Tobacco Company on cigarette sales at football games, and a 10-day vacation in Cuba.

For years, critics had condemned the violence of American football, which annually resulted in more deaths than prizefighting.  Reform was finally initiated after the slaughter of the 1905 college football season, during which 18 deaths had occurred.  President Theodore Roosevelt met with officials from Harvard, Princeton, and Yale, urging them to set strict standards in order to save the sport.  In late 1905, 60 colleges and universities established what became (in 1910) the National Collegiate Athletic Association (NCAA) to govern college sports.  

In 1906, the rules committee, under the leadership of Walter Camp, made several significant changes to the game.  They legalized the forward pass; reduced game time to one hour, with two 30-minutes halves; increased from 5 to 10 the yardage needed to retain possession; banned jumping over opponents; added a second referee; and, required that substitutes report to the referee.  In 1910, pushing and pulling were banned, and two years later the number of downs was increased to four and the field decreased to 100 yards, with 10-yard end zones.