Mark's illustrations have appeared in children's books and magazines such as Appleseeds, Cobblestone and Cricket. A book that Mark wrote and illustrated for upper elementary readers, Raising 'La Belle,' (Eakin Press) about the recovery of an early colonial shipwreck in Texas won the Western Writers of America Spur Award for the year's best western juvenile nonfiction book. (2003.) A Bag of Lucky Rice, illustrated by Mark and written by George Reichart (David R. Godine, Publisher) was named a Smithsonian Notable Children's Book of the Year.

As a contributing editor for American Artist Watercolor magazine, 
Mark interviewed many of the top children's book artists who use watercolor (and other water-based mediums) including Jerry Pinkney, E.B. Lewis, Emily Arnold McCully, Patricia Polacco, Ashley Wolff and Ted and Betsy Lewin. 

Escape from Illustration Island named his blog, How to Be A Children's Book Illustrator "one of the  top online resources on children's book illustration." 

For the past 12 years Mark has taught classes in children's book illustration at the Art School of the Austin Museum of Art/Arthouse in Austin, Texas.

Snce 2009 his online course, Make Your Splashes - Make Your Marks! has attracted students from around the U.S. and the world.  

Aztec marketplace, illustration by Mark Mitchell for Appleseeds