The categorical stability of 523 students with mild handicaps during their school years was investigated in a retrospective study of special education records in three high schools. The students had final classifications as learning disabled (LD), educable mentally retarded (EMR), emotionally disturbed (ED), and speech impaired (SP). Twenty-four percent had at least two different classifications during their school years. In analyzing stability of classification according to the initial category designation, the least stable category was SP, and the most stable was ED. Of the students who changed classification sometime during their special education history, most had changed to one different category, but some had changed to two different categories. Most of the changes took place during the secondary years. The ED and EMR categories tended to receive proportionately more members from other categories than did the LD and SP categories. The SP category tended to receive few members from other categories of handicapping conditions, while the LD category received an intermediate number relative to its large size. The strongest predictor of reclassification was initial classification in the SP category.