The intellectual origins of information organization (IO) as a field of study are examined by tracing the use of the terms, "information organization", "knowledge organization", "bibliographic control", and their variants, and by surveying the educational texts dealing with the various component activities of IO, along with reports and discussions of corresponding curricula, across the twentieth century. Analysis reveals that the notion of a single, composite field covering cataloguing, classification, indexing and the other IO activities, only became established in the late twentieth century, mirroring the broadening of the Library and Information Science curriculum toward that advocated by the "iSchool" movement. Prior to this, three phases of curriculum development are identified: the teaching of cataloguing and classification as distinct fields in the initial decades of Library Science education; these two activities then being taught as the combined field of "cat and class"; and, a growing coverage of other activities of "bibliographic control" from the 1960s onwards, such as those emphasizing the "subject approach" to IO. This last phase can be seen as a precursor to the establishment of IO as a generic field of study. The validity and prospects of the field are discussed in light of the historical account.