1978 NFL season

The 1978 NFL season was the 59th regular season of the National Football League. The league expanded the regular season from a 14-game schedule to 16. Furthermore, the playoff format was expanded from 8 teams to 10 teams by adding another wild card from each conference. The wild card teams would play each other with the winner advancing to the playoff round of eight teams.

The season ended with Super Bowl XIII when the Pittsburgh Steelers defeated the Dallas Cowboys.

Major rule changes

 * To open up the passing game, defenders are permitted to make contact with receivers only to a point of five yards beyond the line of scrimmage. This applies only to the time BEFORE the ball is thrown, at which point any contact is pass interference. Previously, contact was allowed anywhere on the field. This is usually referred to as the "Mel Blount Rule"
 * The offensive team may only make one forward pass during a play from scrimmage, but only if the ball does not cross the line and return behind the line prior to the pass.
 * Double touching of a forward pass is legal, but batting a pass towards the opponent's end zone is illegal. Previously, a second offensive player could not legally catch a deflected pass unless a defensive player had touched it. This is usually referred to as the "Mel Renfro Rule". During a play in Super Bowl V, Baltimore Colts receiver Eddie Hinton tipped a pass intended for him. Renfro, the Cowboys defensive back, made a stab at the ball and it was ruled that he tipped it ever so slightly (which he denied) into the arms of Colts tight end John Mackey, who ran for a touchdown. Later, this rule was also the one in question during the Immaculate Reception in 1972. But despite these two incidents, the rule change did not occur until this season.
 * The pass blocking rules were extended to permit extended arms and open hands.
 * The penalty for intentional grounding is reduced from a loss of down and 15 yards to a loss of down and 10 yards from the previous spot (or at the spot of the foul if the spot is 10 yards or more behind the line of scrimmage). If the passer commits the foul in his own end zone, the defense scores a safety.
 * Hurdling is no longer a foul.
 * A seventh official, the Side Judge, is added to the officiating crew to help rule on legalities downfield. The addition of 15 officials (one per crew) forced three-digit numbers to be used for the first time.

Interconference Scheduling
With the start of a 16-game season also marked the start of a new scheduling format that saw a division in one conference play a division in another conference, rotating every season and repeating the process every three years, similar to the current format for interleague play for Major League Baseball. Previously, teams played random opponents in the other conference. The format remains in effect today, though it was slightly modified over the years, most recently with the addition of two more divisions in 2002.

The interconference matchups for 1978 were as follows:
 * AFC East vs. NFC East
 * AFC Central vs. NFC West
 * AFC West vs. NFC Central

The initial format matched the two four team divisions together (AFC Central & NFC West) while the other divisions were placed together. The format wasn't perfect, as each team played only four teams from each division except in the four-team divisions. Intraconference play would remain random until 2002, when it also adopted the division format while the other two teams would be from whatever place that team finished last year.

Division Races
Starting in 1978, ten teams qualified for the playoffs: the winners of each of the divisions, and two wild-card teams in each conference. The two wild cards would meet for the right to face whichever of the three division winners had the best overall record (or, if the winner of the wild-card playoff was from the same division as that team, the division winner with the second best overall record). The tiebreaker rules were based on head-to-head competition, followed by division records, common opponents' records, and conference play.

Final standings
W = Wins, L = Losses, T = Ties, PCT = Winning Percentage, PF= Points For, PA = Points Against

 – clinched wild card berth, – clinched division title

Tiebreakers

 * New England finished ahead of Miami in the AFC East based on better division record (6–2 to Dolphins' 5–3).
 * Buffalo finished ahead of Baltimore in the AFC East based on head-to-head sweep (2–0).
 * Oakland, Seattle, and San Diego finished 2nd, 3rd, and 4th, respectively, in the AFC West based on better record against common opponents (6–2 to Seahawks' 5–3 and Chargers' 4–4).
 * Minnesota finished ahead of Green Bay in the NFC North based on better head-to-head record (1–0–1).
 * Los Angeles was top NFC seed over Dallas based on better head-to-head record (1–0).
 * Detroit finished ahead of Chicago in the NFC Central based on better division record (4–4 to Bears' 3–5).
 * Atlanta was the first NFC Wild Card based on better conference record than Philadelphia (8–4 to Eagles' 6–6).
 * St. Louis finished ahead of N.Y. Giants in the NFC East based on better division record (3–5 to Giants' 2–6).