D.W. graduates from a tricycle to her first two-wheeler and under Arthur's careful guidance learns the basics of bicycle safety. After learning the basics of bicycle safety from her big brother Arthur, D.W. prepares to take off her training wheels and ride into the sunset with her friends and family.

When D.W. is sent to her room as punishment for making baby Kate cry, it is Kate who finally makes her feel better.

D.W., Arthur's little sister, tells all about what it is like to be in preschool, including essential information about such topics as bathroom breaks, storing things in a cubbie, and sharing at play time.