We investigated the reliability of the Education-related Self Efficacy Scale (ESS-40), a measure of self-efficacy at a core task level designed for people with psychiatric disabilities. Sixty community residents with schizophrenia or schizoaffective disorder participated. The ESS-40 was administered twice via telephone interview. Short cycle test-retest reliability was very good for the total score and most items. The measure demonstrated signs of a coherent internal structure, adequate face validity, good client acceptability, and promising utility. The reliability evidence supports its use in community mental health services and in psychiatric rehabilitation settings. Sensitivity and predictive validity require further investigation.