In 1995, the prototype BÜCHERSCHATZ, an online public access catalogue for children, was developed in interdisciplinary cooperation between students and professor Ursula Schulz of the Department of Library and Information Studies of Fachhochschule Hamburg, a designer, and Ute Külper and Gabriela Will, two computer scientists of Hamburg University. The target group for BÜCHERSCHATZ are children at the age of 8 to 10. Developing BÜCHERSCHATZ we followed a model of software development called STEPS. While prototyping we used several methods of user participation, namely the metaphor game, scenarios and PICTIVE. BÜCHERSCHATZ has an attractive graphical user interface, is mouse-driven, uses a metaphor arousing children's curiosity (treasure hunt), presents topics of children's books as a defined amount of search categories tested with children, and encourages reading through book descriptions appropriate for children.