This document compares and contrasts dictionary catalogs and classified catalogs. A dictionary catalog lists all entries alphabetically by author, title, subject, etc. A classified catalog has some number entries and some word entries, with materials arranged in two parts: a classified section by class number and an alphabetical index. A classified catalog allows for easier assessment of collection strengths and weaknesses by subject and shows relationships between subjects. It is more suitable than a dictionary catalog for large, specialized libraries and preparing subject bibliographies. However, a dictionary catalog is easier to use and maintain subject entries in the alphabetical section.