The nonparametric approach to test theory discussed here has its roots in the early work of Guttman, Lazarsfeld, and Meredith; and more recently in the work of Cliff and in Tatsuoka and Tatsuoka. Mokken's extensive treatment of this subject concentrated on defining, constructing, and testing unidimensional scales, based on responses to dichotomous items. His emphasis is on the development of formal statistical methods to extend and support the use of descriptive indices. The analyses described assume the existence of a scale such as might result from one of Mokken's procedures. Based on responses to items forming the scale, inferences are made regarding the abilities of individuals. In this sense, the work described is viewed as an extension of Mokken's developments and includes a discussion of the following: (1) basic assumptions and notations; (2) alternative ordinal assumptions and corresponding definitions of ability; (3) minimal assumption (relative consistency) and analysis; and (4) an example of an analysis. (PN)