Dissertation submitted to the Department of Psychology, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Arts. / The aim of the present study was to develop and evaluate a process model linking stressful environmental change, perceived job insecurity and stress reactions, A review of the literature revealed that stressful changes in the environment are linked to individual stress reactions, Stress theory has also recognised that appraisal of a stressful situation leads to stress reactions, Moreover, the literature has identified job Insecurity as a form of appraisal in that it is an internal event reflecting a transformation of beliefs about what 's happening in the organisation and environment. Job insecurity in turn has been shown to result in various stress reactions in individuals, Based on such research and theorising, a causal model was developed and tested using structural equation modeling techniques, It was assessed whether: stressful environmental change impacted upon stress reactions and job insecurity; job insecurity impacted upon stress reactions; and whether Job insecurity operated as a form of appraisal in mediating the relationship between stressful environmental change and stress reactions, The Independent variable, stressful environmental change, was specified as a common factor of the measured variables, political change, social change and organisational change, The proposed mediator variable, job insecurity, was specified as a common factor of the measured variables perceived threat to total job multiplied by powerlessness, and perceived threat to job features multiplied by powerlessness, The dependent variable, stress reactions, was specified as a common factor of the measured variables psychological distress, job dissatisfaction and reduced organisational commitment. The model was tested empirically using a combined sample of 267 subjects from three organisations, Results indicated that all relationships In the proposed model were confirmed, and that a reasonable fit was demonstrated between the empirical data and the theoretical model. Stressful environmental change was causally related to both stress reactions and Job insecurity, Job Insecurity was causally related to stress reactions, and in addition operated as a partial mediator between stressful environmental change and stress reacdons. Conceptual and methodological reasons for the findings are discussed, as well as some theoretical and practical implications, Limitations in the methodology are identified and future considerations of research are suggested, / AC2017