When I Love Lucy premiered in October 1951, it was filmed in a way that had never been done for television. Desi Arnaz insisted on filming before a live studio audience using three cameras simultaneously—a technique borrowed from stage theater but adapted for film. This allowed editors to cut between angles and capture authentic audience reactions. Every other filmed television show at the time was shot single-camera, with laugh tracks added later.

The multi-camera format became the standard model for situation comedies and has remained so for more than seventy years. Every filmed sitcom that uses live audiences—from The Mary Tyler Moore Show through Seinfeld through The Big Bang Theory—works in the tradition that Arnaz established at Desilu.

I Love Lucy became the most-watched show in American television. Its success gave Desilu the financial resources to expand. In 1957, the company purchased the former RKO Pictures studio facilities in Hollywood for $6 million—33 sound stages at two locations, including the lot at Melrose and Gower where generations of films had been made. Desilu was suddenly one of the largest production companies in Hollywood.

In 1960, Lucille Ball and Desi Arnaz divorced. Ball bought out Arnaz's share of the company for $3 million. In doing so, she became the first woman to head a major Hollywood production studio—at a time when the major studios were almost entirely male-led, and when the idea of a woman exercising that kind of institutional control was genuinely novel.

Under Ball's leadership, Desilu produced some of the most durable television of its era. The Untouchables, which dramatized FBI agent Eliot Ness's battles with organized crime in Prohibition-era Chicago, was a hit. Mission: Impossible launched in 1966 and became a franchise that would last into the twenty-first century. Mannix ran for eight seasons.

The most consequential decision Ball made at Desilu was one she later admitted she didn't fully understand at the time: she approved funding for a science fiction pilot called Star Trek, created by Gene Roddenberry. The NBC network wasn't interested in buying it. Desilu kept it alive through a second pilot. Star Trek premiered in September 1966. It ran three seasons in its original form and became one of the most significant entertainment franchises in history.

In 1968, Lucille Ball sold Desilu Productions to Gulf+Western Industries for $17 million. The studio and its properties became Paramount Television—the name under which many Desilu productions continued to be known and distributed.

Ball remained active in television for years afterward. But the Desilu era, from 1950 to 1968, represented something specific: a window in which two people—one of them a woman, one of them a Cuban immigrant, both of them performing artists rather than studio executives—reshaped the infrastructure of American entertainment. The portmanteau name outlived the marriage and eventually outlived the company. It has never quite stopped meaning something.