We present the design and evaluation of an interactive children’s book. It is implemented as an interactive web site, where children worldwide can create collages around a common theme and add them to the constantly growing book. After a discussion of usability for children and their access to art and computers, we describe the design and implementation of the book. We evaluated our design in two studies with 35 school children between 10 and 15 years of age, using the techniques of thinking aloud and constructive interaction. In the process, we identified and fixed a number of usability problems and gained additional insights for the design of this kind of interactive web applications for children.