Traditionally, a major form of organized bowling has been throughleague competition. Leagues are typically groups of two- to five-player teams that compete with one another over the course of a 28- to 36-week season, generally starting in September and ending in the spring. Summer leagues are often offered with a much shorter schedule of 10 to 15 weeks, usually starting in May. Additionally, "short" (8- to 12-week) season leagues are now offered in many bowling centers to entice bowlers who may not want to commit to a "long" season league. These "short" leagues generally start around September/October and January/February.

In most leagues, teams of one to five individuals bowl three games (called a "series") each. A typical league will schedule their teams to bowl two at a time against each other on each pair of lanes the league uses each week. Usually the winner of each game is decided by adding up the scores of all teammates (plus a team "handicap" in most leagues). Leagues typically decide standings by awarding a certain number of points for each team game win. Additionally, points are usually awarded for total pinfall for each team over the course of the series (commonly referred to as "total wood"). Some common methods for calculating points in a given three-game match include:

• 3-point system (one point per game)
• 4-point system (one point per game, one point for total wood)
• 7-point system (two points per game, one point for total wood)
• 8-point system (two points per game, two points for total wood)

The 7- and 8-point systems are favored, because a tie game can result in each team getting one point. (In a 4-point system, half-points would be required for ties.) Throughout the course of a season, each team will usually face all of the other teams in scheduled competition. "Position Rounds", where 1st place bowls against 2nd place, 3rd place bowls against 4th place, and so on, are often added at one or more points during the season.

There are some leagues that are organized as "match point" leagues. In these leagues, each bowler on a team bowls "head-to-head" against his opponent for points, and, along with the team game points and total wood, the point system can total 30 or more.

Leagues can have various formats. While most leagues are mixed leagues, containing both men and women, men's and women's leagues are still common, along with junior leagues for young bowlers. There are also different types of competition. Scratch leagues are those in which the actual pin count determines the winner. Most leagues are not scratch, but handicap leagues.

In handicap leagues, the scores are a combination of the actual pins knocked down, plus addition of a handicap value, to give teams with lower averages a chance to compete against teams that have higher averaged bowlers. The handicap system provides a means to compare scores across the whole league. When computing averages, however, resultant totals that have a decimal component (numbers to the right of thedecimal point) discard all numbers to the right of the decimal point, leaving only awhole number, asrounding any decimal number equal or higher than 0.500, "up" to the next highest whole number when calculating averages is prohibited byUSBC rules on scoring in tenpins.

The number of league bowlers peaked at 8 million in 1980,^[1] declining to approximately 1.57 million in the 2014-2015 season.