The following changes were adopted to add tempo and action to the game  and to help counter the proposed changes announced by the World Football League to their games:
One sudden death overtime period (originally 15 minutes; since 2017, 10) was added to all preseason and regular season games; if no team scored in this period, the game would result in a tie. This rule was enacted to decrease the number of tie games. The first ever regular season overtime, a September 22 game between the Pittsburgh Steelers and the Denver Broncos, ended in a 35–all draw. It was not until November 10, when the New York Jets defeated the New York Giants, 26–20, that an overtime game would produce a winner. Since the 2012 season teams get one possession to score unless the team scores a touchdown or safety.
Goal posts: moved to the end line from the goal line, where they were since 1933. This was to reduce the number of games being decided on field goals, and to increase their difficulty, as well as to reduce the risk of player injuries.
Missed field goals: The defensive team takes possession of the ball at the line of scrimmage or the 20-yard line, whichever is farther from the goal line. (In 1994, that reference to the line of scrimmage was changed to the kick spot, which is usually 7 yards behind the line of scrimmage.) Notice that the 25-yard line (since 2018) is where the defense takes possession after a touchback.
Kickoffs: moved to the 35-yard line (from the 40-yard line) to reduce touchbacks, promoting more excitement with kickoff returns, through 1993 and since 2011. From 1994 to 2010, the kickoff was moved farther back, to the 30-yard line.
Punt returns: members of the kicking team cannot go beyond the line of scrimmage until the ball is kicked, except the player at the farthest end of each side of the snapper. The original rule change would have prohibited any player from crossing the line of scrimmage prior to the ball being kicked.
An eligible pass receiver can only be contacted once by defenders after the receiver has gone 3 yards beyond the line of scrimmage.
When the defensive team commits an illegal use of hands, arms, or body foul from behind the line of scrimmage, the penalty will be assessed from the previous spot instead of the spot of the foul.
The penalties for offensive holding, illegal use of hands, and tripping were reduced from 15 to 10 yards.
Wide receivers blocking back towards the ball within three yards from the line of scrimmage may not block below the waist.
In addition to the on-field rule changes, the league eliminated the "future list" of players a team could sign without placing them on an active roster. The future list had been formalized by the league in 1965 and had informally existed for over a decade before that. The concept would return in 1977, renamed the practice squad.
From 1970 to 2001, there were three divisions (Eastern, Central and Western) in each conference. The winners of each division, and a fourth “wild card” team based on the best non-division winner, qualified for the playoffs. The tiebreaker rules were changed to start with head-to-head competition, followed by division records, records against common opponents, and records in conference play.
Note: Prior to the 1975 season, the home teams in the playoffs were decided based on a yearly rotation. Had the 1974 playoffs been seeded, the AFC divisional matchups would have been #3 Pittsburgh at #2 Miami and #4 wild card Buffalo at #1 Oakland; the NFC matchups would not have changed, although #1 Los Angeles would have had home field for the NFC championship game due to its head-to-head victory over #2 Minnesota in week 11.