MUCH has been written about the effect of strabismus on vision, and since the time of Claude Worth1poor vision as a result of disuse in strabismus has been increasingly recognized. Since this time, also, less emphasis has been placed on the effect of vision on strabismus. It is our purpose to point out certain things in the relationship of vision and squint. Little need be said about the fact of amblyopia ex anopsia. It is now well established that most visual defects associated with squint are the result of the squinting and subsequent disuse of the affected eye. Prior to Worth it was generally felt that there was much organic visual defect—congenital amblyopia—and that the squint resulted from the poor vision. In this paper, a portion of our file of private cases of strabismus will be analyzed. The factors in determination of vision in children will be commented