The problem of medication adherence in schizophrenia spectrum disorders (SSDs) has challenged researchers and clinicians for decades. Few investigations have examined non-psychiatric adherence in this group. We conducted a descriptive correlational investigation of adherence and related factors in 185 stable outpatients with SSDs. Fifty-seven percent of participants had antipsychotic medication levels within therapeutic range and 42% had levels below therapeutic range. Pill count percentage adherence to antipsychotic medications ranged from 0–100% with a mean of 70% and SD 34.9. Mean non-psychiatric medication adherence ranged from 0 to 100 with a mean of 61% and SD 31.8. The following characteristics were not significantly associated with adherence: age, diagnosis, gender, race, living arrangement, educational level, typical versus atypical antipsychotic medication. Level of symptoms was correlated negatively and significantly with self-reported medication adherence and medication adherence self-efficacy. Our next project will examine the effectiveness of a telephone-delivered intervention designed to support adherence in this group.