“American Idol” once again drove Fox’s ratings to the rafters during the second week of May sweeps.

The musical reality series is helping propel the network to what looks like wins for the May sweeps ratings period and the season among the adults 18 to 49 demographic.

For the first two weeks of sweeps, which began April 27, Fox ranked as the No. 1 network in the advertiser-friendly demo with a 4.4 rating, a number that includes live-plus-same-day viewing, according to Nielsen Media Research.

While Fox is enjoying ratings increases over last year’s May sweeps, all of its broadcast competitors are suffering declines. Fox is the only network so far to show any growth from the same time period in 2005 among both adults 18 to 49 and total viewers.

“Idol” gives Fox a much-needed boost when it premieres every January, helping the network offset the beginning of the season in the fall, which suffers programming disruptions owing to postseason baseball games. “Idol,” despite its gargantuan audience, is unlikely to directly boost the network’s fall 2006 fortunes, said Bill Carroll, VP and director of programming for Katz Television Group.

“What ‘Idol’ can do is help a couple of the summer shows they will relaunch this year,” he added.

The most obvious recipient will be “So You Think You Can Dance,” the reality dance competition that begins its second season with a two-hour special Thursday, May 25, the day after the “Idol” finale. Expect numerous plugs for “Dance” in the last weeks of “Idol,” plus mentions of its other returning summer reality series, “Hell’s Kitchen,” Mr. Carroll said.

“Both of those shows had a good sampling last year, and with ‘Idol’ [they will have] an even larger audience base to start from,” he said.

“Kitchen” premieres Monday, June 12, at 9 p.m. (ET)

If “Dance” and “Kitchen” build on their solid performances from last season, they could provide a platform on which Fox could promote its fall lineup. If the success of “Prison Break,” which premiered last August, is an indicator, Fox is likely to launch at least one of its new dramas in August, which puts it in even closer proximity to “Dance” and “Kitchen.” At least one new drama already in production, “Vanished,” is a prime candidate for an early launch date.

May sweeps always means a heavy schedule of season and series finales, but this year the ratings period also means the de facto finales for two networks: The WB and UPN, which are being shuttered to make room for the CBS Corp./Warner Bros. Entertainment network The CW.

The fact that both networks are going away has not dampened viewers’ interests in The WB’s and UPN’s finales. The May 8 one-hour season finale of UPN’s “Girlfriends” scored a 1.7 in adults 18 to 49, its best performance since February and up 31 percent from its performance the previous week. UPN’s “Veronica Mars” season finale May 9 gave the show its best performance on the night since moving from Wednesdays in April. “Veronica” scored a 1.1 in adults 18 to 49 and garnered 2.4 million viewers.

After 10 seasons, The WB’s “7th Heaven” aired its purported series finale May 8, attracting its biggest audience in total viewers-7.6 million-since January 2005. “Heaven” scored a 3.0 in the adults 18 to 49 demo, coming in third in the 8 p.m. hour and beating the first hour of ABC’s “David Blaine: Drowned Alive” special (2.8) and CBS’s “King of Queens”/”How I Met Your Mother” comedy block (2.7). Despite the episode’s being advertised as a finale, negotiations were ongoing last week to bring “Heaven” back for another season on The CW.