Diagnostic tools provide data to assist educators in designing individualized instruction and intensifying intervention for students who do not respond to validated intervention programs. Diagnostic tools can be either informal, which are easy-to-use tools that can be administered with little training, or standardized, which must be delivered in a standard way by trained staff. Teams may find it helpful to initially consider using more informal and easily accessible diagnostic tools and data to avoid loss of instructional time. Standardized diagnostic tools, which require more time to administer and interpret, may be required for students who continually demonstrate a lack of response or who require special education.