This study evaluated the use of an online catalog by 33 children in the fourth, sixth, and eighth grades. As a basis of comparison, the children's ability to use the card catalog was also evaluated. Touch screen terminals were used to access a CLSI catalog. A specific set of tests was developed to determine if children have the necessary developmental skills to effectively locate and interpret bibliographic information as presented by both forms of library catalogs. The children studied did not have a broad knowledge of alphabetizing or filing conventions. They were moderately successful in using the card catalog (65% of the searches were successful), whereas only about 18% of the children were successful in the online searches. The students in the study preferred to use the card catalog over the online catalog. There were few differences between males and females. In general, fourth graders were the least skilled, eighth graders the most skilled, and sixth graders moderately skilled. It is recommended that software be designed that uses natural language, fewer screens, and clearer help messages. Library instruction needs to be more effective, and librarians need to be aware that children's skills are limited in using either type of catalog. Five references and a 12-item bibliography of library skills manuals are included. (Author/MES)