The CW will launch a two-hour Sunday primetime block for the 2018-19 broadcast season, expanding its linear lineup of original programming from five nights a week to six.

The move represents a vote of confidence in the CW and its business model from parent companies CBS Corp. and Warner Bros., both of whom signed off on it, as well as from affiliates, who will hand a night of programming back to the network.

“We’re very, very happy and very optimistic,” CW president Mark Pedowitz told Variety. “We believe that this is the best thing for the CW and its business model.”

When the CW launched in 2006, it did so with a Sunday programming lineup. But the night proved to be a tough field to compete in for the then-fledgling network, born from the combination of the WB and UPN. In 2008, the network struck a deal with Media Rights Capital, essentially leasing over a five-hour Sunday-night block to the independent producer. That scheme failed, and in 2009 the CW gave Sunday evening back to its affiliates.

Since that time, the television landscape has changed dramatically. Under Pedowitz, who joined in 2011, the CW has shifted its programming strategy, moving from an audience makeup that skewed hard female to a near-even gender balance, and increasing its median age to aid affiliates leading into their evening-news broadcasts. It has also pursued a digital strategy that emphasizes its own platforms, CWTV.com, an ad-supported platform where it stacks recent episodes of its original programs, and CW Seed, a digital venue for short-form content.

The CW has become a money maker for its parent companies through their deals with Netflix to stream past seasons of shows produced for the network. The current Netflix deals are set to expire in a year and a half. The Sunday expansion gives the CW more shelf space for original series, an indicator that the parent companies have found that producing shows to air on the network then live on via streaming distribution in subsequent years has been profitable.

Pedowitz said that discussions with the parent companies about expanding began in earnest in July, and approval came in December.

“I think everyone is pleased,” Pedowitz said. “This move is a win-win-win for the CW, for our affiliates, and for our owners.”

For affiliates, the prospects of seeing the CW program primetime on Sundays — giving it 12 hours of original programming per week, up from 10 — is now far more attractive than it was a decade ago. In recent seasons, the network, which draws smaller audiences than the Big Four and skews significantly younger, has countered broadcast trends, showing ratings stability and even flashes of growth. In Nielsen live-plus-seven numbers, the network is currently averaging 1.8 million primetime viewers (up 3% from last season) a 0.5 rating in the 18-34 demo and a 0.6 rating in the 18-49 demo (both even). It has found critical and commercial success with female-skewing dramedies such as “Jane the Virgin” and “Crazy Ex-Girlfriend”; superhero action dramas such as “Flash” and “Arrow”; and new series “Riverdale” and “Black Lightning.”

“I heard a lot of feedback saying that it gave [affiliates] something to talk to the MVPDs about to try to up their retrans fees,” Chris Brooks, executive vice president of network distribution, said of the expansion, which he worked with affiliates to secure clearance for. “It gave them something to sell on Sunday nights outside of syndication. It was really well received.”

The move back into Sundays, which will go into effect in the fall, has prompted an uptick in development. The network has ordered eight pilots for 2018-19 — in addition to a planted pilot for a likely “Supernatural” spinoff — after ordering six last season and greenlighting four to series.

The CW plans to air 15 original scripted shows this season. Pedowitz said that the network plans to air as many as 20 next season.