Purpose: This study aimed to understand the effects of the Cognitive Orientation to daily Occupational Performance (CO-OP) on successful engagement in desired occupations (goals), health-related quality of life, and caregiver stress for individuals with Parkinson’s Disease (PD)-related cognitive impairment and their caregivers. Methods: A mixed methods single-subject design was used. Quantitative and qualitative data were combined to gain a comprehensive understanding of results. Results: Participants successfully engaged in all three trained goals and both untrained goals, generalized CO-OP strategies to perform trained goals outside of treatment sessions, and transferred CO-OP strategies to perform untrained goals independently. Conclusions: Individuals with PD-related cognitive impairment are capable of successfully engaging in self-selected treatment goals that are trained during CO-OP sessions, generalizing CO-OP strategies they have learned in treatment in order to perform the same goals outside of treatment, and transferring CO-OP strategies in order to perform untrained goals independently. / October 2016