During the early 1980s, Itek Optical systems and the United States Air Force developed and published an Image Interpretability Rating Scale based on a set of image interpretability criteria specific to military operations. There appears to be a similar need for a commonly understood and used scale to describe the relative resolution of aerial photographs in fields of environmental concern. Using our extensive backgrounds in image acquisition and use and in assessing problems common to natural resource managers, we set out to develop an image rating scale. Our objective was to more clearly relate image characteristics (such as scale, spatial resolution, spectral resolution, and format) to specific examples of image interpretation tasks which are performed by environmental scientists. To do this, we created rating scale categories and established the minimum resolution requirements in terms of ground resolved distance for a variety of typical environmental features. We found that our needs for image quality closely parallel needs in military intelligence. This information will provide designers of image acquisition systems specific criteria to consider in addition to more abstract resolution measures such as lines per millimeter. We suggest that this IIRS will compliment the earlier Itek scale and like it, will become a standard for discussions of image quality and resolution.