This dissertation is a response to the call for theoretically coherent practical methods which encourage and facilitate systemic thinking in psychology (Boden, 1972; Jordaan & Jordaan, 1984; Lazarus, 1990; Norcross & Grencavage, 1990; Von Bertalanffy, 1968; Winburn, 1991). Teleonics is a developing ecology of process-based systems ideas, where process is foregrounded relative to structure. From a teleonics perspective, structure and process are viewed as inextricably linked, while the foregrounding of process is viewed as having significant implications for how meaning is constructed from observations. Given the dominance of the structure-based orientation to psychology during the modern period, a process-based systems approach is a contribution to the development of postmodern thinking in psychology. Through a process of reviewing the systems thinking literature, and illuminating those premises that point to a distinction between process- and structure-based thinking, the following process-based systems premises are punctuated: * life is essentially of a process nature, * nature is approximate rather than definite, * organization in nature is dynamic, * systems function according to principles of autonomy and integration, * creation is a process of emergence and * teleos is a character of living systems. By relating these premises to the field of psychology, further premises of governance and the union of opposites are punctuated. A review of selected psychological literature is provided to draw distinctions about how the abovementioned process-based systems premises relate to psychological theory and practice. In line with the postmodern trend to coherence between theory and practice, teleonics is proposed as a contribution not only to creative theory building but, also to application. In support of coherence between theory and practice in psychology, epistemological tools and tasks for systemic intervention are discussed. The methodological approach of this dissertation is consistent with the conceptual theorist style (Reason & Rowan, 1981 a). A systems methodology, namely that of double description (Bateson, 1979; Keeney, 1983) is used to connect the theoretical and the applied aspects of this study. The theoretical aspect of the double description was formulated by a review, synthesis and integration of the literature. The applied aspect was formulated by means of a report on fieldwork undertaken in the form of a series of case studies. A particular contribution of this dissertation is the specification and illustration of three teleonics maps namely, spiral mapping, teleos mapping and telentropy tracing. The application of these maps is presented via an elaborated format case study of an individual adult therapy case, and four further cases presented in a circumscribed format (Carlson-SabeIli & Sabelli, 1984). The circumscribed case studies include a single session intervention and a health enhancement workshop. The methodology of this dissertation can be located in new paradigm (postmodern) research. The soundness of endeavour (Reason, 1988c) of this dissertation can be appreciated in relation to validity in terms of the philosophical ideas supporting new paradigm research. Other contributions are that it promotes convergence and informed divergence in psychological theory, is an example of the development of systems theory at the level of micropractice, explores the concept of levels in psychology, and contributes to the further development of teleonics as a process-based systems ecology of ideas. The introduction of visual maps, as practical non-verbal tools for the communication of concepts and observations in psychological practice, is a particularly useful contribution. In this dissertation, teleonics is demonstrated as a process-based systems model which facilitates the practical operationalizing of process-based systems thinking.