Two of the principal issues, which have been addressed in assessments of the benefits of web-based instructional systems, are firstly, whether the segmentation of information provided by the web structure aids users in apprehending the interrelationships between the units of information featured in the web. Secondly, whether providing the user with an overview of the web system assists in facilitating his/her learning. It is suggested in the present study that these two issues may be more effectively understood by a consideration of an individual's cognitive style. Fifty participants were assigned to one of two web-based instructional systems featuring information on the subject of psychological ethics. The information in one of the web systems was segmented to a greater degree than the information in the other. Half the participants using each web system were given an overview of the system and half were not. After a given time using the system, participants were tested on the information from the web. The findings suggest that cognitive style and segmentation had an effect on performance, although the provision of the overview had little effect. The results are discussed in terms of a consideration of cognitive style in the design of web-based instructional systems.