This study investigates the influence of structure and reading-manipulation, and more importantly, the interaction between these two variables on usability of hypertexts. Four types of hypertexts are distinguished, differing in structure (hierarchical, or hierarchical with partial linearity) and readingmanipulation (scrolling or paging). A fifth extra hypertext containing a hierarchical structure with partial linearity and both paging and scrolling was also investigated. The information itself, a city guide about Utrecht with cultural and tourist information, was exactly the same in all hypertexts. Three aspects of usability were examined: efficiency, ease of learning and user-satisfaction. These aspects are measured by performance on 24 search tasks and a task reflecting insight into the structure of the hypertext. Also, questions about the structure of the hypertext and satisfaction with the system had to be answered. The results indicated that structure and reading-manipulation did not interact. There were, however, significant main effects of structure and reading-manipulation. A purely hierarchical structure was frequently more usable than a hierarchical structure with partial linearity, and scrolling appeared to be more useful than paging. The fifth alternative hypertext seemed slightly more usable than the hypertexts with linearity, but less usable than purely hierarchical hypertexts. The findings combined suggest that a purely hierarchical hypertext with scrolling is most useful, probably because this structure and kind of reading-manipulation both provide a clear insight into the structure of the hypertext. We assume this insight to be necessary for adequate performance.