The primary aim of the study will be to examine Social Cognitive Theory (SCT) correlates, of physical activity (PA) participation and health-related quality of life (HRQoL) in Parkinson's disease participants.

The body of evidence in the physical therapy and rehabilitation literature supports that physical activity is associated with improvements in quality of life for Parkinson's Disease (PD) patients. However, few studies have examined the underlying variables that may account for this relationship in PD patients. Researchers have examined stages of readiness to exercise in PD patients and barriers to exercise and found a strong association between self-efficacy and exercise in PD patients, rather than disability .

Researchers suggest that social cognitive theory (SCT) constructs are important correlates of physical activity for PD patients and should be targeted in interventions. A more comprehensive study of SCT correlates - Self-Efficacy (SE), Outcome Expectations (OE), and Self-Regulation (SR) should provide a better understanding of the factors that contribute to physical activity participation and the physical activity / health-related quality of life relationship in PD patients.

Inclusion Criteria:

1. English speaking
2. Parkinson's disease diagnosed by a neurologist

Exclusion Criteria:

1. Atypical Parkinson's
2. Supranuclear Palsy
3. Deep Brain Stimulation (DBS) or other brain surgery
4. Not living independently (living in assisted-living or skilled-nursing facility)
5. Spouse or caregiver responding instead of PD participant

The investigators are using a cross-sectional experimental design of 404 geographically diverse Parkinson's participants. Physiologic (Hoehn & Yahr) and psychological (surveys and single-item measures) measures will be collected via web-based surveys in Qualtrics accessed through a link.

Sample Using (Fritz & MacKinnon, 2007) article on the required sample size necessary to detect mediated effects, using the empirical estimates in Table 3 for the Baron and Kenny test with ť = .59, α = .59 and β = .14, the desired sample size needed for a power of .8 would be 404. In this population, the investigators expect that some PD participants may start the survey and be unable to finish. For this reason, the investigators would like to oversample by 25% with a target of 505 participants.