As a coach, he was known for championing the once-outlawed dunk, which he characterized as a "high percentage shot," and for clutching a brightly colored red-and-white polka dot towel on the bench during games.

In 1964, his recruitment of the program's first African-American players, Elvin Hayes and Don Chaney, ushered in an era of tremendous success in Cougar basketball.

[2] The dominant play of Hayes led the Cougars to two Final Fours during the 1960s and sent shock waves through Southern colleges that realized that they would have to begin recruiting black players if they wanted to compete with integrated teams.

Lewis's Houston teams played a key role in two watershed events that helped to popularize college basketball as a spectator sport.

In January 1968, his underdog Cougars, led by Hayes, upset John Wooden's undefeated and top-ranked UCLA Bruins 71–69 in front of 52,693 fans at the Houston Astrodome.

In the early 1980s, Lewis's Phi Slama Jama teams at UH gained notoriety for their fast-breaking, "above the rim" style of play as well as their overall success.

Lewis retired from coaching in 1986 at number 20 in all-time NCAA Division I victories, his 592–279 record giving him a .680 career winning percentage.