Evidence is presented regarding the construct validity and internal consistency reliability of scores for an investigator-developed individualized family service plan (IFSP) rating scale. One hundred and twenty IFSPs were rated using a 12-item instrument, the IFSP Rating Scale (McWilliam & Jung, 2001). Using principal components factor analysis procedures, a three-component solution was derived. The obtained components were labeled Outcome Writing, Natural Environments Practices, and Outcome Selection. Acceptable score reliabilities were obtained on total scores and for each component. The IFSP Rating Scale demonstrated that writing, planning for intervention in natural environments, and outcome selection were components of quality in IFSPs.