This thesis proposes a re-conceptualisation of engineering practice that moves towards responding to the nature of our 21st Century (21C) predicament – the dynamic, turbulent, labyrinthine flux which has developed through the inhabitation of modern humanity in our open living world.  It describes a philosophy and practices to achieve this. Key concepts are the context within which practice takes place and an integrated approach at the system level. Together these principles promote processes and practices that can design life situations which are more desirable and feasible, not only for humanity but to strengthen our natural environment. This is active adaptive planning; it changes practitioners’ relationship with the world by providing spaces where the agenda is not “driven” by the “push” of the past but elicits the “pull” of future intentions. Using these approaches people are engaged collectively in processes that re-connect with context taking into account the relevant uncertainties across what are often articulated as “different” systems (e.g. social, environmental, technical) and between past, present, future. Further, it works the loops – performing ontological politics that is linking and knotting what emerges from these processes with all the potential stakeholders, mobilising resources, peers, allies and the public.  The thesis identifies links between Socio-Technical Systems, Actor-Network Theory and process philosophy. This extends Actor-Network Theory which has already removed those intellectual constructs that disarticulated reality, focusing attention on practise, movement, the making and remaking of reality, or net-work-ing with the complex heterogeneous nature of agency. It envisages practitioners having an epistemology and ontology that is formed through being “out-and-about” in the world, making “translations”.  Through embedding these ideas in the way engineers learn and in the processes that they use, engineering becomes a “putting through”, manoeuvring, dissolving boundaries, always being in action, moving towards sustaining with others, while recognising purpose, congruence and transforming as emergent properties. Through purposive imag(in)ing of different ways of sustainable doing and being integration can occur, reframing across methodology, epistemology, ontology and philosophy