The Geriatric Institutional Assessment Profile (GIAP) is a self-administered survey of hospital nurses designed to assess a hospital's readiness to implement geriatric programs. The GIAP measures nurses' knowledge and attitudes toward older adults as well as the organizational attributes that support or constrain geriatric best practices. Test-retest reliability estimates of the GIAP were conducted with a sample of 166 direct care nurses in three urban, university-affiliated hospitals over a 3-week time period. Intraclass correlation coefficients of GIAP scales and subscales ranged between .82 and .92, demonstrating good to very good reliability. The GIAP is a reliable measure of organizational attributes of the hospital relevant to geriatric care.