Discovering a set of domain classes during object-oriented analysis is intellectually challenging and time consuming for novice analyzers. This chapter presents a taxonomic class modeling (TCM) methodology that can be used for object-oriented analysis in business applications. Our methodology helps us discover the three types of classes: (1) classes represented by nouns in the requirement specification, (2) classes whose concepts were represented by verb phrases, and (3) hidden classes that were not explicitly stated in the requirement specification. Our approach synthesizes several different class modeling techniques under one framework. Our framework integrates the noun analysis method, class categories, English sentence structures, checklists, and other heuristic rules for modeling. We illustrate our approach using a detailed case study and summarize the results of several other case studies. Our teaching experience shows that our method is effective in identifying classes for many business applications.