This research effort was directed at the development of legibility prediction models for flat-panel electronic displays used under typical office illumination (i.e., fluorescent) and various phases of daylight illumination. The models are intended to permit the manipulation of candidate display technologies and pertinent display characteristics such that legibility is maximized with respect to specified viewing conditions. Further, the legibility prediction models are intended to serve as an aid to the display designer in the intelligent selection of a display device for a known application. Critical legibility parameters were identified and relevant display measurement techniques were developed. A multiple degree of freedom daylight simulation apparatus capable of simulating the desired office and daylight illumination was designed and constructed. Reading speed performance data was collected from 14 subjects representative of both an age 18 to 30 group and an age 50 to 70 group. Each subject performed a numeral identification task using seven candidate flat-panel display technologies under 120 different symbol subtense/illumination/viewing angle arrangements. In addition, complete display characterization through microphotometric and microradiometric measurements was conducted for the seven flat-panel technologies under each of the viewing conditions. The results of the experiment revealed significant differences and complex interactions among the display technologies and viewing conditions which provided an excellent basis for the development of legibility prediction models. Extensive regression analyses were performed in which the human performance data was compared to both the critical legibility parameters and the display characterization measurements. Multiple sets of technology-based legibility prediction equations were successfully derived for each age group along with a generalized flat-panel display legibility prediction model. The models developed permit the evaluation and comparison of candidate display devices based on predicted reading speed as an indicant of legibility for a specified viewing environment. The required display characterization measurements can be collected in the field or under simulated conditions using commercially available hand-held measurement devices. In the absence of specific measures, careful estimation through comparison with similar display measurements contained in this report may be acceptable for certain applications. In their final form, the legibility prediction models serve as an aid in the evaluation and selection of electronic displays for a known application. In addition, the generalized legibility prediction equation developed holds the potential for application to other similar display technologies beyond those flat-panel candidates examined in the present study. Further, use of the models may permit the evaluation of new displays and display concepts without the immediate need for purchase, prototype construction, or complicated simulation. / Ph. D.