St. Stephen's is accredited by both the Independent School Association of the Southwest (ISAS) and Southwest Association of Episcopal Schools (SAES).
ISAS and SAES are members of the NAIS Commission on Accreditation and have voluntarily submitted to a rigorous and impartial review of its accreditation program and demonstrated its adherence to the Commission’s Criteria for Effective Independent School Accreditation Practices. ISAS and SAES are commended by NAIS for the quality of the Association’s accreditation program for their Member Schools.
ISAS and SAES are recognized by state agencies in the six states they serve, including the Texas Private School Accreditation Commission (TEPSAC). SAES is recognized by eleven Episcopal dioceses within its region.