In the 17 1/2 years since the Fox network first signed on, "That '70s Show" stands alone. It is Fox's first and only long-running, live-action sitcom that's a genuine hit.
Oh, the network has certainly had success with animated comedies ("The Simpsons," of course, will soon become the longest-running comedy of any kind in TV history.) And with dramas and reality shows.
But live-action sitcoms? "That '70s Show," which airs its 150th episode on Sunday (7:30 p.m., Ch. 13), stands so far ahead of the rest of the pack it's completely alone.
Which isn't exactly what anybody was expecting when the show premiered in August 1998. Not even the cast members.
"I was cast out of a high school play," said Topher Grace, who stars as Eric in this sitcom about a group of teenage friends in the 1970s. "I think . . . the best part of the experience has been being part of an ensemble, seeing how valuable it is to work with kids your age who are so talented and then to have mentors and great writers. . . . Everyone kind of makes everyone else better."
"When I first started, I didn't know what a great show was or anything," said Laura Prepon (Donna). "I didn't even know what ratings were. All I knew was that our chemistry was amazing and everybody watching us felt like we'd grown up together."
"I think it's such a great, fun experience and such a great ride," said Wilmer Valderrama (Fez). "The writers have done a great job keeping it fresh."
And keeping it fresh for the audience is the challenge for the writers.
"I was going to say the biggest challenge is how to avoid getting to 1980," joked executive producer Jackie Filgo, who pointed out that the six young characters started out in high school but are now facing adulthood.
"They're taking on more serious adult relationships, dealing with jobs and their futures. So it always gives us a fresh crop of stories."
Like Sunday's 150th episode, when Eric and Donna start having second thoughts about their impending wedding. Which may or may not take place in Wednesday's 151st and 152nd episodes (7 and 7:30 p.m., Ch. 13).
Wedding or not, "That '70s Show" will return in the fall for its seventh season. And, for a live-action Fox sitcom, that's unprecedented.
E-mail: pierce@desnews.com