Health care and educational legislation and policy require that clinicians demonstrate, using measurement and report of outcomes, accountability for services rendered. Clinical algorithms have been developed and are used by various health care professionals to assist with hypothesis generation and systematic clinical reasoning; however, they do not explicitly guide measurement of outcomes as part of the reasoning process. Schaaf and colleagues developed the Data-Driven Decision Making (DDDM) process to address the greater need for outcome measurement, systematically support decision making, target intervention more precisely, and measure and document outcomes. This article describes the application of the DDDM process with a child with ASD who received occupational therapy using Ayres Sensory Integration^®.