Purpose This study aimed to develop a colleague solidarity scale for nurses and to verify its validity and reliability. Methods Initial items were extracted through an extensive literature review and in-depth interviews with twelve clinical nurses. These items were subjected to content validity testing by ten experts and face validity testing by five nurses.
Subsequently, the final tool was developed using a validity and reliability test comprising 53 preliminary items. Survey data were collected from 548 hospital nurses. Results In the exploratory factor analysis, four factors and 33 items were selected, yielding a total cumulative variance ratio of 66.7%. Through the confirmatory factor analysis, the final tool consisting of 4 factors and 31 items was developed. The factors were as follows: “mutually beneficial community,” “nurse identity.” “rigid organizational experience,” and “supportive interaction.” These factors were verified through convergent and discriminant validity testing. The internal consistency reliability was acceptable (Cronbach’s ⍺= .94). Conclusion This tool can serve as the basis for developing programs and strategies to strengthen solidarity among nurses by identifying the current level of colleague solidarity among hospital nurses and enhancing their understanding of it.