Disney Channels Worldwide has earmarked March 23 as the launch date for the much-anticipated US 24/7 preschool net Disney Junior. Disney XD in the US, meanwhile, is launching a dedicated Marvel programming block, Marvel Universe, on April 1.

Disney Junior, which began as a daily Disney Channel programming block in February 2010, has seen its year to year ratings increase 26% among kids ages two to five and 36% among boys ages two to five. With Disney Junior airing in the US, the basic cable/satellite channel now joins 28 other Disney Junior channels worldwide and will be available via cable and satellite providers including Comcast, Time Warner Cable, Cablevision, Bright House Networks and Verizon.

The channel’s lineup will feature Jake and the Never Land Pirates and Mickey Mouse Clubhouse, and new series Doc McStuffins will premiere at launch. A new short-form series A Poem Is… will also be featured, as well as a weekend movie block, Magical World of Disney Junior, and new interstitials featuring Disney characters Sebastian and Flounder from The Little Mermaid, Mrs. Potts and Chip from Beauty and the Beast, and Lucky and Pepper from 101 Dalmatians.

Disney XD’s Marvel Universe will feature exclusive Marvel content, new animated short-form series, live-action interstitials and the return of The Avengers: Earth’s Mightiest Heroes series. The creative team behind the Marvel Animation-produced Ultimate Spider-Man includes Marvel COO Joe Quesada, Paul Dini (Batman: The Animated Series), and Man of Action Studios (Ben 10 and Generator Rex).