For over 20 years, the National Imagery Interpretability Rating Scale (NIIRS) has served as a standard to quantify the interpretability or usefulness of imagery. The need for a NIIRS arose from the inability of simple physical image quality measures, such as resolution, to adequately predict image interpretability. The NIIRS defines the levels of image interpretability by the types of tasks an analyst can perform with imagery of a given rating level. The NIIRS provides a simple, yet powerful, tool for assessing and communicating image quality and sensor system requirements. While the scale itself is simple, the process of developing the scale is both complex and resource intensive. Rigorous methods are needed to: develop appropriate image interpretation tasks, relate these tasks to the various levels of image quality, and validate that the scale is usable in practice and has the desirable properties of a rating scale. This paper presents three different NIIRS corresponding to three types of imagery. Visible, IR, and Radar. The paper also discusses the methodology used to develop and validate these rating scales.