We examined the unique and shared contributions of pain catastrophizing, cognitive pre-sleep arousal, and somatic pre-sleep arousal, to the prediction of insomnia severity in chronic pain. Forty-eight adults with chronic pain completed self-report measures of these study variables, health, and mood. Hierarchical regression showed that pain catastrophizing accounted for unique variance in insomnia severity, independent of pain intensity, depression, restless legs symptoms, and demographics. However, when cognitive and somatic pre-sleep arousal were also taken into account, the significance of cognitive pre-sleep arousal rendered pain catastrophizing non-significant. We identify research and clinical implications of this study.