A questionnaire was developed to measure changes in certain behaviors at various intervals after correction of refractive errors in a sample of mentally retarded persons. The sample comprised three age groups: 0 to 6 years, 7 to 17, and 18 and above. In each age group, four subgroups were selected--one experimental (new-glasses) group and three control groups. In the group which received new spectacles, changes were recorded in social behaviors, gross and fine motor skills, and reading and writing skills. These changes were most evident in the youngest age group.