With this thesis, I present to you the result of my Ph.D. research, an endeavour that began six years ago. Challenged by Professor Dr. Celeste Wilderom and Dr. Desirée van Dun, I was prompted to merge my 30 years of practical knowledge with academic research. ipv , I accepted this challenge. My research question emerged from a realization during my years of practical experience:witnessing numerous organizations struggling with the successful execution of improvement initiatives. This pervasive challenge became the focal point of my academic pursuit. In addressing this practical problem, I endeavoured to explore, from a scientific perspective, the root causes behind organizations' struggles. My goal was twofold: to gain theoretical insights and, maybe for me as a consultant even more important, to derive practical results through academic research. I aspired to unearth insights and recommendations capable of enhancing the effectiveness and success of organizations and their employees in complex problem-solving challenges so that successful operational improvements are taking place.Today, as I reflect on the completion of this journey, I am not only pleased with the fulfilment of my academic responsibilities but also gratified by the prospect of contributing substantively to the practical realm. This research is not merely an academic exercise but a tangible effort to bridge the gap between theory and application, with the ultimate aim of fostering organisational and human-(group) effectiveness and/or success in overcoming challenges. The importance of this study is underscored by the prevailing era of constant change in which we live. In order to maintain vital, organisations must adequately respond to this ever-changing landscape. When perceiving non-performing processes, the situation must be improved. And for this it is a must that organisations and their employees have the capability to effectively solve complex problems.Originated in this practical challenge, this academic research has provided many insights into the intricacies of executing a high-quality process improvement relevant to all organisations and their employees worldwide. I am content that I am enhancing literature with these insights and that the results of this research are very well applicable in practical work lives of people and organisations.