This study is a methodical research to develop a health behavior assessment scale for patients with rheumatoid arthritis, and to test the validity and reliability of the instrument. The research procedure was as follows; 1) The first step was to develop conceptual framework based on a comprehensive review of the literature, in-depth interviews patients with rheumatoid arthritis. This conceptual framework was organized in eight dimensions; pain management, exercise, rest, diet control, active committment, self-management, positive thinking, interpersonal maintenance. Initially 56 items were selected from 164 statement. 2) These items were reviewed by panel of eight specialists and the Index of Content validity (CVI) was calculated, and forty six items were selected which met more than 70% on the CVI. 3) 174 rheumatoid arthritis pateints were interviewed, and data was gathered from Jan. 25 to Feb. 18, 1999 for test reliabilities and validities of the scale. The item analysis was carried out and 40 items were selected. Factor analysis by varimax rotation was carried out to test construct validity. The internal consistency by chronbach's alpha was calculated. The findings were as follows; 1) Item analysis and factor analysis were carried out to test the validity of the health behavior assessment scale. The item analysis was based on the corrected item`s to total correlation coefficient (.30 or more), and information about the alpha estimate. However, this was only if this item was deleted from the scale. As a result of the item analysis, forty items were selected. Thirty items were selected by a initial factor analysis by varimax rotation, and ten items were deleted because of factor complexity. In the secondary factor analysis, eight factors were labled as 'positive thinking', 'exercise', 'rest', 'pain management', 'active committment', 'self-management', 'diet control', and 'interpersonal maintenance', each similar with the conceptual framework. 2) Chronbach's alpha coefficient to test reliability of the scale was. 903 for total the thirty items. The Scale for assessing health behavior developed in this study was identified to be a tool with a high degree of reliability and validity. Therefore this scale can be effectively utilized for assessment in the health behaviors of the patients with rheumatoid arthritis.