In a general way it may be said that to think in terms of systems seems the most appropriate conceptual response so far available when the phenomena under study--at any level and in any domain--display the character of being organized, and when understanding the nature of the interdependencies constitutes the research task. In the behavioral sciences, the first steps in building a systems theory were taken in connection with the analysis of internal processes in organisms, or organizations, when the parts had to be related to the whole.