This study investigated the effects of end-user search experience on searching behavior in the use of an online information retrieval system by monitoring the QUICKLAW searches of a group of law students over a 1-year period. Searching behavior was examined in these aspects: Searcher command and feature repertoires (i.e., the set of commands and the set of features such as Boolean operators and truncation used), language usage patterns (command and feature use frequencies, state chains of first to third orders, and search effort measures), error patterns, search speed, learning approaches, and attitudes towards the search system. Results showed that search experience affected several aspects of end-user behavior, including the increase of participants' command and feature repertoires, some change of overall language usage patterns as reflected in the significant differences in the frequency distributions of commands and features used, increase of search speeds, and change of learning approaches. However, experience did not result in searchers making fewer errors or being helped to recover from errors.