The standard layout model used by web browsers is to lay text out in a vertical scroll using a single column. The horizontal-scroll layout model--in which text is laid out in columns whose height is set to that of the browser window and the viewer scrolls horizontally--seems well-suited to multi-column layout on electronic devices. We describe a study that examines how people read and, in particular, the strategies they use for scrolling with these two models when reading large textual documents on a standard computer monitor. We compare usability of the models and evaluate both user preferences and the effect of the model on performance. Also interesting is the description of the browser and its user interface which we used for the study. Categories and Subject Descriptors H.4.3 [Information Systems Applications]: Communications Applications--Information browsers; H.5.2 [Information Interfaces and Presentation]: User Interfaces; I.7.2 [Document and Text Processing]: Document Preparat...