BACKGROUND: The study of workers' health problems possibly associated with stressful conditions requires valid and reliable tools for monitoring risk factors. The present study validates two questionnaires to assess psychosocial risk factors for stress-related illnesses within a sample of Colombian workers. METHODS: The validation process was based on a representative sample survey of 2,360 Colombian employees, aged 18-70 years. Worker response rate was 90%; 46% of the responders were women. Internal consistency was calculated, construct validity was tested with factor analysis and concurrent validity was tested with Spearman correlations. RESULTS: The questionnaires demonstrated adequate reliability (0.88-0.95). Factor analysis confirmed the dimensions proposed in the measurement model. Concurrent validity resulted in significant correlations with stress and health symptoms. CONCLUSIONS: "Work and Non-work Psychosocial Factors Questionnaires" were found to be valid and reliable for the assessment of workers' psychosocial factors, and they provide information for research and intervention. Am. J. Ind. Med. © 2012 Wiley Periodicals, Inc.