The UIL was originally created by the University of Texas at Austin in 1910 as two different entities, the Debating League of Texas High Schools (to govern debating contests) and the Interscholastic Athletic Association (to govern athletic contests).

From 1940 to 1970, an era of racial segregation in Texas, the Prairie View Interscholastic League (PVIL), headquartered at Prairie View A&M University, served as a separate parallel organization for African-American public high schools in Texas.

Previously, both schools were members of the now-defunct Texas Christian Interscholastic League (TCIL); after that league's demise and their inability to gain admittance into the Texas Association of Private and Parochial Schools (TAPPS) or Southwest Preparatory Conference (SPC), they decided to further pursue their decade-long battle of gaining membership into the UIL.

As a state agent, the UIL must treat individuals equally and show the purpose/need as well as a rational basis for eligibility restrictions.

[citation needed] All students must abide by the state No Pass No Play law.

Activities for most Texas private schools are governed by separate bodies, the largest of which is TAPPS.

The conferences are A (the smallest), AA, AAA, AAAA, AAAAA and AAAAAA (the largest).

The two eligible teams with the highest student enrollment for its district are seeded in the Division I playoff bracket, and the remaining two teams (with the lower enrollment) are seeded in the Division II playoff bracket.

For all other 11-man conferences and for six-man football, the UIL divides schools into separate Division I (large) and Division II (small) districts at its biennial redistricting session (in these cases, there are a maximum of 16 districts statewide, as opposed to the 32 in the larger conferences); separate playoffs are held for each division with the top four teams (top two in six-man) from each district eligible.

Exceptions include the following: The UIL One-Act Play contest is a competition where similarly sized Texas schools present an 18-40 minute play and may be adjudicated by a panel of three judges or a single judge.

These rules are in place to ensure safety, allow for equity, satisfy legal standards, and make the running of the contest practical.

[15] All individuals or ensembles who are given an overall Division I (based on the consensus of each judge's rating) may advance to the next level, except for area and state marching band competition (which use an alternative system).

All schools of all conferences compete in region, area, and state competition annually as a fall semester activity.

The number of bands that advance to state from finals is likewise determined by contest size.

State competition uses a similar format to area, with a preliminary and final round always being held.

Concert and sight-reading is divided into 3 divisions: band, orchestra, and vocal, and is held in the spring semester.

[18] In solo and small ensemble competition, held in the spring semester, conference alignments are disregarded.

The state semifinal and championship games for all five classes in boys and girls basketball were previously held at the Frank Erwin Center on the campus of The University of Texas at Austin.

In 2015 it was decided to move the boys & girls state tournaments to the Alamodome in San Antonio, TX, due to ongoing price and venue disputes in Austin.

The soccer semifinals and finals for 4A and 5A are held at Birkelbach Field in the Austin suburb of Georgetown, and the state baseball tournament is held at Dell Diamond in another Austin suburb, Round Rock.

The state softball tournament is held at Red and Charline McCombs Field on the UT Austin campus.

The state cross-country meet is held at Old Settlers Park in Round Rock.

From 2000–2011 the girls' volleyball tournament was held in Strahan Coliseum on the campus of Texas State University in San Marcos.

Between athletics, music, theatre, spirit (cheer) and academics, UIL estimates that half of all public high school graduates have competed in at least one UIL-sanctioned event during their high school tenure.

[21] In the 2016–17 season, the University Interscholastic League featured 834,558 participants, with 59% boys and 41% girls.

[22] The sports with most boys are: The sports with most girls are: Any student who competes at a state academic meet (at any high school grade) is also eligible to apply for a scholarship from the Texas Interscholastic League Foundation, an affiliate of UIL.

The student must attend college in Texas full-time and meet certain grade requirements.