The purpose of this study was to test an expanded model of Rosabeth Moss Kanter's Structural Theory of Organizational Behaviour (Kanter 1977; Laschinger, Finegan, Shamian and Wilk 2001) by examining the relationship between nurses' empowerment and their perceptions of effort-reward imbalance (Siegrist 1996). A sample of 112 staff nurses employed in teaching hospitals in Ontario participated in this study (58% return rate). A descriptive correlational survey design was used to collect data by eliciting responses to five self-report instruments: the Conditions of Work Effectiveness II, the Job Activities Scale II, and the Organizational Relationships Scale II (Laschinger, Finegan, Shamian and Wilk 2001), the Effort-Reward Imbalance (ERI) scale (Siegrist and Peter 1999a) and a demographic questionnaire. Staff nurses were only moderately empowered, and 24.1% perceived their work to have more efforts than rewards, according to Siegrist's guidelines.

The final model revealed that structural empowerment had significant direct effects on both ERI and psychological empowerment (b=.46) and ERI (b=-.31). The path between psychological empowerment and ERI was not significant (b=-.01), i.e., after the effects of structural empowerment were accounted for, psychological empowerment explained no additional variance in effort-reward imbalance. Overcommitment was also significantly related to ERI (0.35). Fit indices for this model met Bentler and Bonett's (1980) criteria, and the model explained 22% of variance in ERI. Contrary to Kanter's theory, both structural empowerment and a personal dispositional variable (overcommitment) were significant predictors of nurses' reports of ERI.