Fox apparently finds “That ’70s Show” groovy. Very groovy.

The network has picked up two full years of the Carsey-Werner laffer, which will guarantee it a spot on the air until at least 2002. That also means Carsey-Werner will accrue enough episodes of the sophomore sitcom to sell it in off-network syndication.

“That’s a lifetime in my business,” joked Doug Herzog, Fox Entertainment prexy, a job that tends to change hands every two years. “This is a show on the rise. It’s a very important piece as we start to put ourselves back in the game.”

Stronger ties

Herzog said he hoped the pickup would signal Fox’s interest in developing a stronger relationship with the independent production house.

“They are without question the preeminent producers of half-hour comedy,” he said.

While not quite a disco inferno, “That ’70s Show” is Fox’s first live-action comedy hit in years. With the half-hour “Ally” a not-so-successful experiment and “Party of Five” quickly eroding, Fox has been stayin’ alive on Tuesdays mostly because of “That ’70s Show’s” strong demo returns.

Carsey-Werner principal Marcy Carsey had expressed concern about “That ’70s Show’s” move to Tuesday nights this season.

“We were terrified,” she said. “We have a lot of faith in the show, but we know even a good show can get lost if it’s not properly scheduled.”

Carsey said Fox and Herzog expressed faith in the series, however.

Vote of confidence

“It gives us a vote of confidence,” she said of the two-year pickup. “When the network is behind it like this, it’s just the best.”

Season to date, “That ’70s Show” has averaged a 5.1 Nielsen rating and 13 share among adults 18 to 49, improving its 8:30 p.m. Tuesday night time period (which admittedly was inhabited last year by the quickly yanked “Costello”) by 42%.

With the exception of “Who Wants to Be a Millionaire,” “That ’70s Show” has been consistently winning the time period in the adults 18 to 49 demographic as well.

But because “That ’70s Show” aired last fall in the primo post- “Simpsons” timeslot, the show is down from a 6.1/14 last year in the adults 18 to 49 demo.

Among other demographics, “That ’70s Show” has averaged a 6.1/18 among adults 18 to 34 (vs. 7.3/19 on Sundays last year), a 5.9/9 in homes (compared to 6.9/10) and 9.3 million viewers (from 11.3 million).

Launch pad

Fox hopes to use “That ’70s Show” as a means to launch some of its new sitcoms. The network will test the series at 8 p.m. next Tuesday to gauge the possibility of the show leading off a night.

“For the longest time we felt we had nothing other than ‘The Simpsons’ to launch half-hours after,” Herzog said. “We certainly look forward to the day we can use ‘That ’70s Show” to put us firmly back in the live action comedy business.”

“That ’70s Show” was created by Bonnie and Terry Turner (“3rd Rock From the Sun”) and Mark Brazill, who exec produces along with Carsey, Tom Werner and Caryn Mandabach.

The show stars Topher Grace, Mila Kunis, Ashton Kutcher, Danny Masterson, Laura Prepon and Wilmer Valderrama as teenagers in late 1970s Wisconsin suburbia.

Herzog said Fox will announce some of its midseason plans in the coming days. The centerpiece of those plans, the half-hour single-camera comedy “Malcolm in the Middle,” could possibly debut after “The Simpsons” at 8:30 p.m. Sundays in mid-January.

Also on the bench: the new claymation half-hour “Gary and Mike,” the new sitcom “Titus,” the new dramas “Dark Angel” and “The Opposite Sex,” the series version of gamer “Greed,” and returning series “Family Guy,” “The PJ’s,” “Fox Files,” “Guinness World Records: Primetime” and “Beyond Belief.”