As we seek both to improve public school education in high technology areas and to link libraries and classrooms on the “information superhighway,” we need to understand more about children’s information searching abilities. We present results of four experiments conducted on four versions of the Science Library Catalog (SLC), a Dewey decimal-based hierarchical browsing system implemented in HyperCard without a keyboard. The experiments were conducted over a 3-year period at three sites, with four databases, and with comparisons to two different keyword online catalogs. Subjects were ethnically and culturally diverse children aged 9 through 12; with 32 to 34 children participating in each experiment. Children were provided explicit instruction and reference materials for the keyword systems but not for the SLC. The number of search topics matched was comparable across all systems and all experiments; search times were comparable, though they varied among the four SLC versions and between the two keyword online public access catalogs (OPACs). The SLC overall was robust to differences in age, sex, and computer experience. One of the keyword OPACs was subject to minor effects of age and computer experience; the other was not. We found relationships between search topic and system structure, such that the most difficult topics on the SLC were those hard to locate in the hierarchy, and those most difficult on the keyword OPACs were hard to spell or required children to generate their own search terms. The SLC approach overcomes problems with several searching features that are difficult for children in typical keyword OPAC systems: typing skills, spelling, vocabulary, and Boolean logic. Results have general implications for the design of information retrieval systems for children.