This chapter provides a basis for project managers and engineers of today’s complex systems in terms of understanding three important system properties: adaptability, resilience, and agility. Adaptability is a system property that deals with the changes and uncertainty in operational environments. When considering adaptability, several concepts should also be considered to deal with unpredictable events. Principles of self-organization is a key concept for engineering of adaptiveness. The most important role of a project manager is to manage the project from inception to deployment by ensuring that the project stays within budget and is delivered on time and with high quality. While agility is embraced widely in software development, other industries also apply agile principles. Resilience definitions vary depending on the context. For some systems, resilience includes returning to the original steady state; for other systems, resilience means rapidly maintaining an acceptable level of operation after a disturbance; and for other systems, resilience means self-organization and adaptation.