Implementing a Response to Intervention (RTI) system could improve overall student achievement and the way in which students with disabilities are identified. In order to evaluate the effectiveness of an RTI system (i.e., "Is our RTI system accomplishing its stated goals?"), a set of data-based indicators are needed. This paper will describe a set of five measure-able indicators from three domains of evaluation that schools can use to obtain frequent feedback on the impact of their RTI system on reading instruction and achievement. The evaluation methodology provides multiple, sensitive metrics that can be used soon after RTI implementation begins, and does not require that schools wait for more long-term, singular outcome measures such as performance on high-stakes tests to determine if the RTI system is functioning as intended. The data used for each indicator and the way in which the data can impact decisions is described. Issues related to RTI evaluation and areas of further research are discussed. (Contains 6 figures and 1 table.)