This study tested the efficacy of selected personality, behavioural, and social/organizational variables as predictors of adaptation to night work. Sixty female student nurses were studied during their first 15 months of shiftwork. Twenty-two worked on rotating day and afternoon shifts throughout, while the remaining 38 began regular night shifts after six months. Psychological symptoms were measured at baseline (Stage 1), six months (Stage 2) and 15 months (Stage 3). Repeated measures analysis of variance revealed a significant shift group x symptoms interaction (p less than 0.05) between Stages 2 and 3. Only the night workers displayed a significant increase (Tukey HSD: p less than 0.01) in symptoms between Stages 1 and 3. Multiple regression analysis revealed that neuroticism and perceived work/nonwork conflict predicted symptoms at Stage 2. Night work, social support from supervisors, and morningness were predictors at Stage 3. These results suggest that organisational, behavioural, and physiological factors moderate the impact of night work on psychological well-being, and personality factors do not.