When George Lucas was directing the original Star Wars in 1977, he set out to make the film he wanted to make. He didn't want producers and company execs bum-rushing him with demands like "We want a disco soundtrack. Are the Bee Gees available?" or "You know what this film needs? A reptile bunny that speaks in a faux-Rasta accent and makes fart jokes." To which Lucas would obviously have replied, "No disco" and "Come on, guys, save something for the sequels."
To ensure creative control, Lucas produced A New Hope through his own production company, Lucasfilm Ltd. He also founded two divisions within the company to realize the visual and auditory effects of that galaxy far, far away: Industrial Light and Magic and what would later become Skywalker Sound.
A New Hope would be the last movie Lucas directed for more than twenty years, finally returning to the director's chair for The Phantom Menace. While much had changed in that time, one thing that hadn't was Lucas's desire for complete creative freedom. So Lucas again chose to produce the film through Lucasfilm Ltd. and asked Rick McCallum to serve as the producer. Lucas himself would assume the role of executive producer.
And why not? Lucasfilm had produced some incredibly successful movies in the decades after A New Hope, including the Star Wars sequels, the Indiana Jones series, and Labyrinth. Even the company's missteps, like Howard the Duck, are at least entertaining—so long as you have some friends over to riff on them with.
Industrial Light and Magic and Skywalker Sound also returned to work on The Phantom Menace. Since the original Star Wars, both companies had become pioneers in their fields. ILM had revolutionized special effects, and in the 90's, it kick-started the computer-generated imagery revolution with its work on films like Terminator 2, Jurassic Park, Jumanji, and, yes, The Phantom Menace.
Skywalker Sound's work has become so influential in the industry that their nomination for an Oscar for Best Sound and Best Sound Editing is as frequent a part of the Academy Awards as overblown red carpet dresses and drawn-out acceptance speeches.
Both companies were nominated for Oscars for their work on The Phantom Menace, but they lost to The Matrix. Still, they helped transfer Lucas's vision to the silver screen, using techniques that were not possible when they first realized that galaxy far, far away. (Source)