The use of general systems theory in the field of instructional systems design (ISD) is explored in this paper. Drawing on work by Young, the writings of 12 representative ISD writers and researchers were surveyed to determine the use of 60 general systems theory concepts by the individual authors. The average number of concepts used by these authors was found to be 18, which included an average of 9.6 of the Group 1 concepts identified by Young (systemic and descriptive factors). A second matrix which showed authors ranked by highest to lowest usage of the concepts indicated that the following 14 concepts were used by 10 or more authors: system, learning, objective, field, isolation and interaction, process, feedback, control, communication, change, boundaries and environment, integration and differentiation, input, and goal. It is suggested that instructional designers should be familiar with the relationship between the ISD field and other disciplines, and should have a working knowledge of basic terms, concepts, and applications of general systems theory. Finally, it is noted that ISD benefits from the use of terms that are more precisely defined in general systems theory than in common usage. The text is supplemented by eight figures and two matrices. (17 references and a 14-item bibliography) (EW)