The New Thought movement is the focus of an exercise in developing a core collection to support research in a defined subject area. The authors outline the New Thought movement's conceptual and historical development and apply this outline to the selection of library resources. A sample collection development policy is included; such a policy is the framework for selection decisions. Special problems and concerns of gathering resources are presented, including library mishandling of this subject in the past. Titles in the core collection are presented, incorporating several types and formats of materials and varied points of view. Lists are given of the contacts, source material and bibliographic references used in assembling this New Thought core collection.