Goal attainment scaling (GAS) is a method of measurement that attempts to tailor measures to the relevant and often unique characteristics of an event, individual, program, or organization. The general approach is common in industry, management, service delivery, and most forms of contractual arrangements or agreements. GAS has quantification characteristics that make it useful in a variety of research and management areas, and it is popularly used as a clinical and educational facilitator. This article describes the method within a recent historical context, relating the method to current thinking and problems in evaluation, and attempts to make the method accessible to potential users. Special emphasis is placed on the use of analyses that assess readiness to change or adopt new practices.