The diagnostic, prescriptive and remediation procedures used in this study were originally developed by Helen Irlen, a California psychologist and researcher. Irlen conceptualized Scotopic Sensitivity Syndrome as a difficulty in visual processing of the printed page when perceived through full spectrum light. Spectral modification techniques were considered controversial in that they were employed prior to scientific validation of the syndrome.Previous research used pre-test/post-test experimental designs to test the effect of spectral modification on reading performance. The 2 research problem addressed here was that the technique had not been systematically examined over time in the school setting, and from the practitioner's point of view.Sample selection involved pre-screening and screening phases.The pre-screening procedures of teacher recommendation and file review resulted in a pool of 26 children who were screened with the Irlen Differential Perceptual Interview Survey. Four subjects were selected who were in separate school settings, who demonstrated Irlen Syndrome to a significant extent, and whose profiles did not present variables which would compromise their participation. These four underwent comprehensive vision evaluations as a preliminary assessment procedure.A four-strand single-subject experimental design was used to generate data on subjects' rate and accuracy of oral reading, and comprehension of silent reading.Performance changes during experimental reading trials varied between the four, although three subjects exhibited positive performance change on one indicator. A supporting procedure was that sUbjects were pre and post-tested on the three performance indicators. Post-test results corroborated the changes demonstrated by three sUbjects.Interview formats were employed to obtain qualitative data from teachers, parents, and the subjects themselves. Recommendations for practitioners intending to implement spectral modification techniques were generated from this data. ACKNOWLEDGEMENTSSpecial education teachers, classroom teachers, building administrators, and media specialists in the schools from which subjects were selected provided valuable support and assistance. The researcher is grateful for their contributions, although the provision of subject confidentiality prevents the identification of persons directly associated with school sites. Although this study included pre-and post-test data, the inquiry was primarily intended to address the extent and direction of change in reading performance over a period of time. The overlays were analyzed as a change factor, operating in conjunction with other influences in the actual school setting.The study was conducted within the time frame of the academic year (approximately nine months), and involved three phases:1. Students for whom spectral modification was appropriate were identified.2. Students selected as subjects had optometric evaluations of their visual systems.3. Subjects used colored transparent overlays for nine weeks, as data on...