The aims of this study were to investigate the construct validity, construct equivalence and reliability of a measuring instrument of job demands and resources, and to assess the differences between the job demands and resources in different organisations in South Africa. Stratified, random samples (N = 2717) of employees in different organizations were taken. Five reliable factors were extracted using principal component analysis with a varimax rotation, namely overload, growth opportunities, organisational support, advancement, and job insecurity. All factors, except organisational support, showed acceptable equivalence for different organisations. Statistically significant differences were found between the perceptions of job demands and resources in different organisations.