1 What little girl doesn’t like a secret hideaway? Interior designer Jillian O’Neill created a cozy curtained nook in this Roscoe Village bedroom. Using lots of clever built-ins, she also maximized storage and workspace.

2 Cars Go Beep wallpaper by Studio Printworks is the fun focal point of architect Julie Fisher’s son’s room. Combined with accents in mossy green, the wallcovering makes the space feel both boyish and pulled together.

3 Architect Charles von Weise worked with Fraser Construction and muralist Jason Brammer to create this imaginative playroom in a Gold Coast townhouse, taking advantage of unusually high ceilings in the basement to create a bi-level “tree house” that kids could climb up to.

4 This play/art room designed by homeowner Leslie Glazier has an imagination-sparking through-the-keyhole feel any kid would love. The chalkboard (a great way to decorate a bare wall fast) introduces a strong and unpredictable contrast color—black—that gets picked up in the storage cabinet, floor covering, and lamp.

Photography:(1) Kate Roth; (2) Stephen Shapiro; (3) Alan Shortall; (4) Eric Hausman

5 The juxtaposition of crisp white walls with an invitingly childlike mural (by Jason Brammer) in bold, high-contrast colors makes this girls’ room feel fresh and modern. The pop of pink at the window was interior designer Alex Jordan’s idea.

6 The high-energy combination of pink and orange makes the perfect backdrop for this sweet room, also by Glazier, while some grown-up but playful touches—a small-scale sofa with a zebra-pattern pillow, a sparkly chandelier—add spunk.

7 Decorator Laura Soskin combined her teenaged son’s interests in art and music and her penchant for decorating with large-scale vintage and salvaged pieces to create a cool room for a growing boy. The funky industrial credenza is the perfect place for stashing clutter.

Photography: (5) Alan Shortall; (6) Eric Hausman; (7) Tate Gunnerson

8 Leo Designs’ Stephanie Wirth drew inspiration from her own childhood in Vienna when designing her son’s sunny second-floor playroom. Black-stained hardwood floors, a red-and-white-striped window awning, and a collection of vintage toys balance European elegance with boyish whimsy.

9 Julie Fisher converted a home office into a sophisticated little girl’s room, pairing the existing mocha-colored walls with youthful (though not overtly kid-ish) modern wallpaper, which, for even more impact, she also put on the door.

10 Using a thick shag rug, a ruffled pink bed skirt, and lilac silk dupioni drapes, designer Hilary Bailes varied texture and mixed toys from different eras to create a lovely, comfortable space worthy of a princess—her daughter.

Photography: (8,10) Tate Gunnerson; (9) Stephen Shapiro