The purpose of this study is to identify trends in the historical development of inquiry and common elements in models of inquiry; evaluate the extent to which inquiry theory has been incorporated in representative inquiry oriented social studies curriculum project materials; and examine problems in curriculum development for inquiry skills. To identify theoretical trends in inquiry models, the writings of inquiry theorists that are relevant to social studies are analyzed. Considerable overlap among theories is found, and six common elements constituting a general model of inquiry are identified: doubt, clarification, hypothesizing, reasoning, testing, and conclusion. Evaluation of the extent to which new curriculum projects have incorporated inquiry theory and processes is based on three projects: Harvard Social Studies Project/Public Issues Series; Holt Social Studies Curriculum; and the Taba Program in Social Science. Analysis reveals all three projects include components of a general model of inquiry, with the exception of doubt. The curricula vary in the extent to which materials and instructional strategies reflect the inquiry orientation expressed in their rationales. Problems examined in the development of inquiry skills include: failure to accommodate student generated problems; minimal provision for individualization; failure to integrate inquiry components; and failure to demonstrate the relevance of inquiry outside the classroom. (Author/JK)