The study examined workers' lay conceptualizations about stress. It used the framework offered by the Kasarek and Theorell's (1990) 'Job Demand-Control-Support' model of stress at work. It assessed the importance workers attribute to the social support factor as a determinant of work stress, as compared with the weights workers attribute to job demand and to job control. It used an assessment technique - the AVERAGE program -- that allows for an estimation of the weight of each factor, independently of the levels of these factors. Sixty-one female and 41 male workers participated in the study. They judged of the stressfulness of work situations described in terms of the three factors. Social support was found to be, by far, the most important factor for judging of the stressfulness of work situations.