Safety is crucial for sustainable growth in organisations and vital for societal progress. Yet, when considering “safety”, one is often confronted with the opposite of what safety is, with a focus on events and occurrences that generate bad consequences. Decisions and actions are ever so often based on past experiences of things that went wrong, making safety habitually reactive. Safety in organisations is directly related to systems that bring about events happening or not happening. It is frequently the case that one reacts to those symptoms, as the solution seems obvious, and immediate action offers a quick relief of the problem symptom. A systemic approach precludes solely reaction to symptoms of events happening, but instead seeks to discover the underlying systems, structures and their associated mental models, in order to understand how the whole system produces its results (wanted and unwanted). Such an approach is necessary, because we live in a VUCA (Volatile, Uncertain, Complex and Ambiguous) world. As a result, organisations in the 21st century wrestle with novel challenges, which are no longer manageable and controllable with the same paradigms and mental models that governed previous centuries. In this thesis I argue that mental models are important human factors. They are the sources of systems, and therefore determine what happens in organisations and society as a whole.Consequently, the following general research question needs to be addressed: “How can organisations proactively generate and improve safety and performance in a volatile, uncertain, complex and ambiguous environment, taking into account sustainability, human factors and mental models?”This research is based on the idea of a design research, where the methodology to pursue and achieve safety and performance proactively is to be seen as the design. In this case, the design consists of appropriate mental models, processes and activities that help organisations to pursue excellence.How one understands and conceptualizes the notions of risk, safety, security, and performance are fundamental mental models. People have an intuitive understanding of these concepts. But how one regards these words determines how one deals with them. Hence, based on an etymological and etiological study of the concepts of risk and safety, and the definition of risk proposed by the ISO 31000 guidance standard, an innovative semantic and ontological foundation for safety and security science is proposed. This foundation provides coherent, standardized notions and definitions of the constructs risk, safety, security and performance, centred on an inclusive understanding of the term “objectives”, to be used as guiding mental models in the design.But what is the significance of mental models for upholding safety in organisations? Risk, safety and security have become ever more important and are also vital to enhance sustainability. The key in achieving safety proactively depends on one’s quality of perception, where the quality of perception should be understood as the level of deviation between reality itself and the perception (mental model) of that reality by an individual or group of people. In our ever more complex and connected world, the safety of systems depends on the awareness and understanding of the interactions and performance of the much smaller sub-systems. Individual behaviours result from individual mental models that generate the gain of achieving and safeguarding objectives, but they also bring about unwanted consequences, causing loss. A proactive way to reach safety of systems is therefore to focus on the performance of the sub-systems at ever deeper levels of detail within the concerned socio-technical systems and determine how mental models affect risk, safety and performance. Implementing appropriate empowering mental models, as well as alleviating harmful ideas, allows to achieve and safeguard objectives, generating safety proactively and eliminating unwanted events. Therefore, to achieve safety and to attain sustainable safe performance, understanding and managing mental models in organisations is of paramount importance.Changing mental models is difficult. The more important they are, the more resistance will be encountered. So, how to change mental models in organizations to proactively improve safety and performance? Mastering mental models in organisations is the fundamental purpose of the design. Generating, adjusting and managing mental models involves a systemic approach, based on dialogue, in order to improve the quality of perceptions in organisations. This requires a systemic view, leadership, leadership skills that enhance dialogue, and the ability to develop a shared vision, mission and ambition, determining what is important and valuable. It allows for aligning individual mental models with those that should govern the system. In doing so, it is possible to create well-aligned corporate cultures that create and protect value and that generate sustainable safe performance. This thesis develops Total Respect Management (TR³M) as a design that acts through an innovative, systemic, organisational culture alignment model. It involves systems thinking abilities, leadership skills and acts as a process to align mental models and objectives with the purpose of the organisation. Furthermore, besides enhancing systems thinking capabilities and leadership skills (directed towards dialogue), ISO 31000 and its guidance is used as a practical tool to undertake and support this alignment process. This makes it possible to generate safe performances in organizations in a sustainable way through continuous improvement. Altogether, these elements define the TR³M design as a concept, set of mental models, a methodology, and a systemic management system. As such, TR³M acts as a design to reach safety and performance in organisations proactively. Unlike many other management systems, the TR³M methodology covers the aspects of leadership, management and continuous improvement in a holistic, systemic and integrated way, linking risk, safety and performance with the individual, organisational and societal objectives to pursue an organisational mission in an innovative, corporate socially responsible manner.But how to implement this pro-active safety management design and improve the performance of organizations of any size or sector, operating in a volatile, uncertain, complex and ambiguous environment? Since TR³M is a holistic and systemic approach, it will likely not work as well as intended and expected whenever parts of the design are not fully implemented. It involves new paradigms, a lot of change and needs education of those who are going to use the design. When executed in the appropriate order, i.e., to start with increasing systems thinking and leadership skills, then implementing ISO 31000 and finally focus on continuous improvement, the accompanying mental models and increased quality of perception should generate the systems needed to reach success.How would one know whether a TR³M implementation works? Measuring results should indicate its success. But how can safety instantly and continuously be measured in a standardised way, independent of the type or size of the organisation? For decades, scholars have been looking at ways to capture the level of safety in organisations, creating complicated measuring systems, capturing a multitude of parameters that have been determined by analysing organisations and their mishaps. But until now, no system is capable of exactly and continuously indicating a quantified level of safety of an organisation. However, starting with the clear and coherent definitions of safety and unsafety, proposed in this thesis, and a clear notion of what unsafety represents in socio- technical systems, combined with the use of a multicriteria model, using specific loss and impact categories combined with impact and severity levels, it is possible to create an aggregated model that can provide a clear and instant indication of levels of safety and unsafety in organisations, indifferent from their size, sector or industry. As such, this innovative measuring system acts as an important feedback loop for the TR³M design, increasing the quality of perception and discovering effects of the much smaller sub-systems, long before they cause harm.