In 1977, Aaron Spelling offered Principal a role in the pilot of his television series "Fantasy Island," which she accepted, however, she stipulated in the contract for the role to be written out as she was planning to attend law school. However, she obtained the pilot audition script for "Dallas" and her career ambitions changed. As Principal explained to TV Guide Network in 2004, "I had left acting to be an agent and was on my way to law school, but when a friend dropped off a "Dallas" script, I read it. When I finished, I knew my life had changed - that part was mine. So I called the person and said, "I'm sending someone in." She said, "Who?" I said, "Just put down my name. It will be a surprise." And it certainly was a surprise - I showed up with me! I sent myself in for it!" Principal landed the role of, Pamela Barnes Ewing, on the long-running prime time TV soap opera series "Dallas" that aired on the CBS network from 1978 to 1991.