Inclusion Criteria:  Moderate to severe methamphetamine use disorder using the DSM-V diagnostic criteria Desire to cease or reduce methamphetamine use  Exclusion Criteria:  Have uncontrolled hypertension or clinically significant cardiovascular disease History of seizure disorder in adulthood CNS metastases or symptomatic central nervous system (CNS) infection Poorly controlled diabetes mellitus Taking certain medications that may interact with psilocybin History of any primary persistent psychotic disorder, including schizophrenia, schizoaffective disorder, bipolar disorder with psychosis, major depressive disorder with psychosis, or schizophreniform disorder History of bipolar I disorder Current eating disorder with active purging History of hallucinogen use disorder Pregnant or breast feeding