Every broadcast network this time of the year has shows whose return for another season is up in the air. But a much larger number of WB and UPN series that in most other seasons would have been ensured an episode order for the fall are facing uncertainty because of the demise of those networks and the creation of The CW.

At least 10 shows currently airing on either UPN or The WB were left out of a Jan. 24 news release announcing the birth of The CW. The network’s partners, CBS Corp. and Warner Bros. Entertainment, listed five WB series and five UPN series as “programming assets” for the new network, shows that many industry insiders say are sure to make up the bulk of The CW’s fall lineup. Those not mentioned are considered particularly vulnerable.

Usually, shows at risk face a waiting game for an additional season order that is predicated on the show’s ratings, the network’s enthusiasm for the series’ creative direction, costs, scheduling needs and the success of the network’s new development.

For The CW, all those elements come into play, but still more factors add complexity to the network’s decision-making process.

Among those factors unique to The CW at the moment: the network’s need to define itself as its own viable network, not as an extension of The WB or UPN, one Hollywood talent agent said.

“It’s got a new personality,” the agent said of The CW. “They have an idea of certain shows they are going to use to launch, but it’s a new game. There’s a lot that’s unknown.”

Another clouding factor is to what extent corporate interests in existing WB and UPN shows will impact the CW schedule.

Among the at-risk shows are The WB’s “One Tree Hill” and UPN’s “All of Us” and “Eve,” all of which have produced just under 70 episodes. An additional year of production is crucial to getting these shows to the number of episodes needed for a syndication run. The shows are all produced and would be distributed in broadcast syndication by one of The CW’s parent companies, Warner Bros. Entertainment.

“Another season makes it easier to strip” the shows in broadcast syndication, said Bill Carroll, VP and director of programming for Katz Television Group, but all three could find a home on cable without an additional season, particularly the one-hour “Hill.”

Shows such as CBS Paramount’s “Half & Half” and “One on One” each have rung up 90-plus episodes airing on UPN. Given that the added costs of another season will not have bearing on whether or not the back-end can be reaped, it could be easier for CW brass to decide to end those shows’ runs. Even if Warner Bros.’ sitcom “What I Like About You” does not make it onto The CW’s prime-time schedule with original episodes, its reruns are expected to end up on the network’s afternoon block come fall.

At least one top CW executive insisted the strategy for forming the network’s new lineup has nothing to do with other corporate concerns and everything to do with what the network needs to attract an adult 18 to 34 demographic. The complete focus for executives at The CW is building a network brand with a schedule that gets viewers to show up quickly, the executive added.

With that mandate, any assumption about what may or may not be picked up for next fall should be tossed aside, another agent said, noting that although The WB announced that “7th Heaven” would conclude at the end of this season, the drama’s 10th, it could wind up coming back for season 11 on The CW.

“The economic issues that were the problem for The WB are not necessarily the same issues for The CW,” Mr. Carroll said.

With financial support from the network’s new partners, “7th Heaven” might have the support it couldn’t get from The WB, which lost $16 million on the show this season, despite a license fee reduction, because of its declining ratings and poor repeatability.

But in the case of “7th Heaven” The CW is no different from The WB. The financial obstacles are still too high for the show to return next season on The CW, the CW source said, noting that it is very unlikely “7th Heaven” would be back for season 11.

Another show getting buzz as a potential CW series is family drama “Everwood,” Mr. Carroll said. With 89 episodes produced through the end of this season, The Warner Bros. drama has enough episodes for a cable run without an additional season, but it could find itself back for the fall.

“It’s still a possibility for being part of what they are putting together,” he said.

While The CW is expected to stick with at least one night of comedy that attracts a large African American audience, the “programming assets” status was given to “UPN’s “Everybody Hates Chris” and “Girlfriends,” and The CW is developing the “Girlfriends” spinoff “The Game.” Those shows potentially fill three of the four half-hour spots needed to schedule a night of programming.

With the addition of The WB’s dramas, the show that gets picked up may be a sitcom that is perceived as more mainstream, Mr. Carroll said.

“All of Us,” which is executive produced by Will Smith, “has a pretty good shot of getting picked up,” he said. “‘All of Us’ is more generic, more ‘Cosby’-esque, and ‘Eve’ is a very ethnic sitcom. Depending how ethnic they are going to go is going to determine what they stick with.”

The lack of a set schedule, unlike the Fox-driven MyNetworkTV, which has been very specific about what programs will make up its fall 2006 lineup, has not been an issue for stations joining The CW, Mr. Carroll said.

“They don’t know what they are going to get,” he said of the new affiliates, noting that the executive auspices, mainly CBS Corp.’s CEO Leslie Moonves, are the driving attractions.

“You’re buying into the concept of Les launching a network,” he said. “Realistically, programs are only going to be there two or three years anyway.”