Introduction This paper describes the development of a posture, force and muscle use assessment tool. Called RULA (rapid upper limb assessment) this tool has undergone initial validation and reliability studies which are also reported upon here. RULA was developed to investigate the exposure of individual workers to risk factors associated with workrelated upper limb disorders. Part of the development took place in the garment-making industry, where assessment was made of operators who performed tasks including cutting while standing at a cutting block, machining using one of a variety of sewing machines, clipping, inspection operations, and packing. RULA was also developed through the evaluation of the postures adopted, forces required and muscle actions of both VDU operators and operators working in a varietv of manufacturing tasks where risk factors associated with upper limb disorders may be present. The method uses diagrams of body postures and three scoring tables to provide evaluation of exposure to risk factors. The risk factors under investigation are those described by McPhee’ as external load factors. These included