PURPOSE: The purpose of this study was to develope a tool to assess mothers' behavior related to health promotion if their preschool children had disabillties. METHOD: The research design was a methodological study. This tool was developed in 4 stages: first, a content matrix as a conceptual framework was developed using Gordon's 11 functional health promotion patterns and 5 categories (Lee, Jung & An, 1996); second, 40 preliminary items were selected through references and interviews with 9 mothers of children with disabilities; third, 2 items were discarded after content validity was done by 3 experts; fourth, reliability and validity were tested with a sample of 243 mothers of children with disabilities who were of preschool age. RESULTS: The final tool consisted of 19 items and Cronbach's alpha coefficient for internal consistency was .82. Five factors were extracted by factor analysis and they explained 55.58% of the total variance. CONCLUSIONS: This tool was identified to have a high degree of reliability and validity. So it can be utilized to assess mothers' behavior in providing health promotion for their children who have disabilities.