Aim. This paper is a report of a study conducted to examine the influence of self-efficacy and affectivity (individual-level variables) and collective efficacy (group-level variable) on nursing performance among hospital nurses. Background. Previous studies of nursing performance, which have focused on individual factor outcomes, have shown limitations. Due to the heavy focus on the analysis of single-level performances, the influence of organizational contextual factors on nursing performance has rarely been studied. Hence, for a better understanding of nurses’ professional development and effective functioning in hospitals, there is a need to study the effects of organizational characteristics as well as individual characteristics on nursing performance. Method. A descriptive-correlational design was used with a convenience sample of 1996 nurses selected from 182 nursing units in 28 hospitals in six metropolitan cities and seven provinces in Korea. Data were collected in 2006 using self-administered questionnaires, which were analysed with using descriptive statistics, Pearson correlation coefficients and multilevel analysis. Results. Individual-level variables, including job position, years of experience, employment status, self-efficacy and positive affectivity were positively related to nursing performance. Collective efficacy and the number of in-service meetings within units were statistically significant group-level variables. Group-level variables reduced the error variances in nursing performance. Conclusion. Understanding the effects of group-level variables on nursing performance improves performance management approaches in hospitals. [ABSTRACT FROM AUTHOR]