Older kids still love to color. I remember getting one of the beautiful Kim's Coloring Books as a child. I loved it so much, I didn't want to color in it. You can still find fancy coloring books by publishers such as Red Farms Studio, Bellerophon, and Dover. For your advanced colorist, I've found lots of extra special coloring pages online.
The Minneapolis Institute of Art's coloring book has many beautiful line drawings of famous art to print and color.
Enchanted Learning has an excellent selection of art coloring pages online. Color line drawings of famous artwork from Cassat's The Boating Party to O'Keefe's Red Poppy.
Do I love illustrators' Mary Engelbreit or Jan Brett coloring pages best? I can't decide; both are my top picks for coloring pages.
There is something fascinating, almost therapeutic about coloring purely graphic designs. The World Wide Quilting Page offers classic quilt designs for coloring. We loved it. Print templates from Totally Tesselated for a similar graphic coloring project that explores geometric principles
Coloring Castle is a new favorite of ours for intricate coloring pages, including some beautiful mandala and geometric pictures to color.
Nature and botanical coloring pages are good selections for advanced coloring. Here are some nice ones.
Folk art drawings are simple but fun for coloring. Many of the designs can be used for other creative projects. Use your imagination!
Fairy tale, digital art coloring books are for sale from Scriptorium. You can also download a few samples to color and print from your computer. Download the zip file at the bottom of the page and unzip to your Windows or Mac to see the samples. Unicorns are another fantasy theme for detailed coloring at Lady Magick's.
Color the flags of the world from this list from Flags of the World. If your child needs to print and color a map for a school project, go to Enchanted Learning's extensive selection of map line drawings.

