Exclusion Criteria: Participants will be excluded if: on-state freezing; hospitalized within the previous three months, a score on the Folstein Mini-Mental Status Exam of less than 25 (indicating significant dementia); non-drug induced psychosis, or drug induced hallucinations, off periods of >25% time (UPDRS part IV)[3] or sub-optimal therapy of Parkinson's disease motor or non-motor symptoms; a second neurological disorder (e.g. stroke) with resulting motor involvement, or poorly controlled or unstable cardiovascular disease that precludes participation in the exercise program. In addition, participants will be excluded if they are participating in another trial except for those investigations that meet the following criteria: 1) PD Trial that is not related to the symptoms of PD (e.g., genetics of PD); 2) stable dose of an investigational medication given to treat motor symptoms of Parkinson's disease on an open-label basis or 3) in a trial that is not expected to affect PD or movement (e.g., hypertension, diabetes). They will be excluded if they cannot speak English and do not have adequate interpretation to participate in all aspects of the study.