It’s ’90s teenage-show nostalgia week on Walt Disney Co. networks, where two new shows are built on memories of series that went off the air just as the current century was starting.

It seems unlikely that the target audience of the Disney Channel is familiar with "Boy Meets World," the warmhearted sitcom that ran on ABC from 1993 to 2000, and it’s only slightly more probable that viewers of ABC Family have spent much time watching "Beverly Hills 90210," the influential drama that ran on Fox from 1990 to 2000. But Disney is the home of "Girl Meets World," a true sequel series beginning Friday, and ABC Family is carrying "Mystery Girls," a comedy with a strong "90210" connection, that started Wednesday.

"Girl Meets World" is more interesting in a conceptual sense: Two of the "Boy Meets World" actors, Ben Savage and Danielle Fishel, return playing the same characters 14 years later. As Cory and Topanga, they’re now married with two children: Riley (Rowan Blanchard) is the girl meeting the world, a middle-schooler (as Cory was in the first season of "Boy Meets World") with a younger brother, Auggie (August Maturo).

The new show, created by the same team (Michael Jacobs and April Kelly) that created "Boy," is less interesting in an adult-viewing sense — this time around, it’s aimed at 6- to 14-year-olds. It has more of the feel of a traditional family sitcom than the louder, jokier competition on Nickelodeon, but the humor is still pretty broad and the plotting blunt for anyone outside that age group. Riley is sweet and prone to having her heart broken; Auggie is weirdly precocious; and Riley’s best friend, Maya (Sabrina Carpenter), is a caustic sidekick in the mold of Jennette McCurdy’s Sam on Nickelodeon’s "iCarly."

"Mystery Girls" is intended for an older demographic, although age would seem to be less important than a general lack of standards. Tori Spelling and Jennie Garth, "90210" stalwarts whose characters there briefly ran a clothing store together, now play actresses who once starred in a television detective series called, yes, "Mystery Girls." The roles play on the performers’ post-"90210" lives and careers: Garth’s Charlie is the uptight mom who’s decamped for the suburbs, while Spelling’s Holly is a tabloid fixture trying to live off her former fame. (Both have teenage daughters who will probably play larger roles as the show goes on.)

Through some predictable coincidences, Holly persuades Charlie to revive their partnership, not as actresses but as actual detectives. This being a mystery comedy, their first case involves tracking down a rumored sex tape made years ago by Holly. The writing is mostly painfully unfunny, but there is one small surprise: Spelling has emerged from her string of junky, increasingly exploitative reality shows as a competent comic actress, effectively deploying her squeaky voice and wide eyes. If only she weren’t given lines like: "Blood, fiber, semen, lay it on me! Away from my face and hair, if you can."

Review by Mike Hale, New York Times