Much of the hypermedia literature instructs developers to "Use a map to prevent users from becoming lost." However, there is very little empirical evidence that maps are effective. In addition, no one has examined how to design the maps to make them most helpful to the users. This research evaluates both issues for information retrieval tasks with a fairly small hypermedia application (about 175 nodes). This study evaluates the overall effectiveness of maps by comparing the subjects' performance using hypermedia without a map to performance with one of four maps. Then, it reveals the relative effectiveness of the different types of maps by comparing the results of the subjects' performance with four variations of a map. In addition, this research evaluates (1) the effects of the experimental conditions on the subjects' mental models of the application and (2) the effects of the subjects' spatial abilities on their performance with hypermedia. The results reveal that there is generally no difference between the subjects' performance with a map and performance without a map. In addition, users who had to navigate using the links within the application rather than selecting nodes from the map (using a "passive" map) viewed more extra nodes, but spent less time on each node and completed the tasks in less time than those who could select nodes directly from the map (using an "active" map). However, many of the subjects using the passive map would have preferred to use an active map. Also, subjects who always had a map available to them (using a "present" map) performed as well as subjects who had to call up a map to use it (a "called" map). In addition, there is no difference in the accuracy of the subjects' mental models. All the subjects understood the application fairly well. A few of the spatial abilities test results are correlated with performance, and all of significant correlations indicate that higher spatial abilities leads to improved performance with hypermedia. It is believed that the lack of differences among the conditions is due to a number of factors, including the simplicity of the application the subjects used and the tasks they performed. / Master of Science