By means of a number of general models the relationships are analysed which are of importance when applying shiftwork systems : for the organization which applies them, its employees, the owners and the community. A quantitative model gives an insight into the shiftwork system which can be regarded as an optimum from an economic angle (depending on the pay level, shift allowances and invested capital). Divergences from the optimum may decrease the rate of return considerably. The outcomes of an analysis of alternatives in a series of companies axe discussed. The approach on the side of companies frequently proves not to be satisfactory. It appears that better information is desirable, with regard to both the economic and the social aspects of shiftwork.