This study aimed to develop a school activity screening tool based on the International Classification of Functioning, Disability and Health (ICF) using the modified Delphi technique (MDT). To collect information about activities needed in schools, nine occupational therapy personnel, five scholars, and six teachers and inspectors participated in the study. Participants were recruited through educational institutions in each city and province and the Korean Society of Occupational Therapy for Child and School. The survey questionnaire comprised six items on participants' characteristics (i.e. sex, age, location in Korea, duration of employment, type of school or institution, and educational level of subjects for occupational therapy) and 153 items in five categories for screening of school activities. Three rounds of MDT were conducted. The data were analysed to compute the mean for each item, and the final items were selected based on the item fit. After three rounds of MDT, 61 items were deleted, 14 from education, 16 from mobility, five from self-care/activities of daily living (ADL), 20 from interpersonal interactions and relationships, and five from communication. This resulted in a final 92 items, which were used to develop the ICF-based school activity screening tool.