The aim of this study was to examine the unique and shared predictive power of psychological variables on reproductive physical health. Three months before fertility treatment, 97 women completed measures of dispositional optimism, trait anxiety, and coping. Information about biological response to treatment (e.g., estradiol level) was collected from medical charts after treatment. Structural equation modeling showed that measured psychological variables were all significant indicators of a single latent construct and that this construct was a better predictor of biological response to treatment than was any individual predictor. This research contributes to evidence suggesting that the health benefits of dispositional optimism are due to its shared variance with neuroticism.