The Individuals with Disabilities Education Improvement Act of 2004 allows schools to use a child's response to research-based intervention (RTI) as a part of procedures to identify students with learning disabilities. This paper considers whether RTI-based assessment models meet ethical and legal standards for acceptable assessment practices. Based on a review of available research, it was concluded that RTI-based assessment practices, when carefully crafted and implemented, have the potential to be multifaceted, fair, valid, and useful. Threats to acceptable RTI-based assessment practices include: the lack of research-based interventions appropriate for diverse academic domains, ethnic groups, grades K-12, and students with limited English proficiency; uncertainty regarding how to determine when nonresponse to intervention warrants formal referral for evaluation of special education eligibility; difficulty translating scientifically sound RTI practices to the local school level; and inadequate staff training and poor treatment fidelity. Suggested directions for future research are included. (c) 2007 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.