The concepts of systems theory and cybernetics have played a fascinating role in the development of contemporary biology and social science. In the decades of the 40s, 50s and 60s, there was much resistance to some of the more grandiose claims concerning the aims and aspirations of the emerging disciplines: that here, indeed, were new paradigms that brought order and unity to interand intra-disciplinary conceptual confusion. What tended to happen was that useful concepts were borrowed by specialists working within particular disciplines and their origins obscured or forgotten. In some cases, the borrowing was curiously partial. In psychology for example, 'information processing' approaches, have deployed cybernetic concepts of feedback, control, information storage and retrieval, but have neglected or ignored the systemic properties of selforganisation. The problem with such partial borrowing is that the baby may be lost with the bath water. A new trend or fashion arises without proper foundations only to be superseded by some other. In recent years, concepts from systems theory have been introduced into the practice of educational psychology. In this essay, I attempt to give some proper grounding for these concepts. In particular, in section 2 I look at what is meant by a social system, arguing that the systemic properties of social institutions, such as families and schools, arise out of the particular nature of persons as social beings and their forms of communication and interaction. In this way, I trust I avoid facile analogising based on the truism that 'the whole is more than the sum of its parts' and leave intact the psychologist's traditional concern with the individual. From the perspective developed, I hope it is clear that, whether he sees it that way or not, the psychologist is always influenced by, and influencing, the systems around him. As a preliminary, in section 1 I briefly overview the chief tenets of systems theory and cybernetics. In section 3, albeit briefly and partially, I examine the implications for the practice of educational psychology as revealed by the systems perspective.