Presented is an instrument (behavior checklist) designed to assess the skill of trainable mentally retarded (TMR) students in performing specific tasks at all levels. Self care, motor, social, and cognitive skills or tasks are categorized according to three levels of competency. The first level includes the development of the very basic performance functions (such as responding to stimuli, first vocalizations). The second level is the building of skills in such basic functions as listening, socializing, motor coordination, dressing, and eating. The third level is using the basic function to specialize (such as to set a table or play games). The checklist is suggested for use at the beginning, middle, and end of the school year to record the student's level of proficiency in each skill area. (KW)