Inclusion Criteria:  Age 40 to 75 Comfortable speaking and writing in English Clinically diagnosed early stage Parkinson's Disease (Hoehn and Yahr Stage 1-3 during an "off" period) who meet DSM-5 criteria for a depressive or anxious disorder and meet all other inclusion and exclusion criteria at screening Currently experiencing depression and/or anxiety (a formal diagnosis is not necessary) Able to attend all in-person visits at UCSF as well as virtual visits Have a care partner/support person available throughout the study Have an established primary care provider, neurologist, or psychiatrist  Exclusion Criteria:  Psychotic symptoms involving loss of insight Significant cognitive impairment Regular use of medications that may have problematic interactions with psilocybin, including but not limited to dopamine agonists, MAO inhibitors, N-methyl-D-aspartate (NMDAR) antagonists, antipsychotics, and stimulants A health condition that makes this study unsafe or unfeasible, determined by study physicians