A lot has been said about change. For example, it is widely recognised that the only constant is change (Heraclitus, 470 BC). As such, no sensible decision can be made any longer without taking into account not only the world as it is, but the world as it will be (Isaac Asimov). As regards this, a bulk of existing researches have been aimed at understanding the triggers for change and the extent or degree to which individuals, organisations, systems or entities have to change. Generally, results from such studies vary. With specific relations to organisations, organisations are advised of the need to develop added adaptive and dynamic capabilities. One of such added adaptive and dynamic capabilities is organisational resilience. In the literature, organisational resilience has been successful linked with organisations ability to maintain long term performance. Hence, the research is not about re-examining the relationship between organisational resilience and organisations ability to maintain long term performance. This research focuses on exploring the critical success factors required to maintain long term performance and building adequate resilience into systems undergoing changes. The investigation was conducted in three phases, namely: (a) the exploratory phase; (b) the descriptive phase; and the empirical phase. The exploratory phase involved identifying the critical factors essential to maintain long term performance and at the same time build resilience into their systems after undergoing organisation-wide changes. In order to make out these critical, a pilot study was conducted. 21 persons occupying senior managerial positions in different organisations were interviewed. The interview data were transcribed, coded and analysed using coding and thematic analysis to identify five common themes, namely (a) employees readiness to support ongoing organisation-wide changes; (b) development of targeted organisational adaptive capacity; (c) the provision of individualised and social support; (d) the use of stress coping mechanisms; and (e) the existence of organisational resilience strategies. The second phase of the research entailed conducting case study research with the intention of describing the identified critical success factors. The final phase entailed conducting empirical analyses and cross case analysis. Results from the cross case study analyses indicated that both resilience building at the individual level and organisational level is needed for organisations to build in resilience into their systems especially after undergoing organisation-wide changes. Three factors (i.e. employees readiness to support ongoing organisation-wide changes, the provision of individualised and social support and the use of stress coping mechanisms) were found to be more pronounced at the individual level. The remaining two factors namely development of targeted organisational adaptive capacity and the existence of organisational resilience strategies are essentially carried out at the organisational level. The research has contributed to the current body of knowledge on how organisations can strive to maintain long term performance, especially for a country like Nigeria where there still remains a dearth of such related studies. Each of the research hypotheses were either confirmed or non confirmed. This will give the practitioners, academicians and managers of Nigerian organisations the opportunity to understand how each of the sub factors of the five critical success factors can influence on attempts to build organisational resilience. In addition, specific actions that managers can follow over the life of an organisation-wide change project that will improve the resilience of systems undergoing change. In addition, differences in how varied control factors can influence resilience building in organisations were explored and validated based on the results of the Mann Whitney test results. At the end of the thesis, recommendations for future practice and research were made. One of such is that resilience building at both levels be done concurrently and given equal prominence.