Agile systems-engineering and agile-systems engineering are two different concepts that share the word agile. In the first case the system of interest is an engineering process, and in the second case the system of interest is what is produced by an engineering process. The word agile refers to the adaptability and the sustainment of adaptability in both types of systems. Sustained adaptability is enabled by an architectural pattern and a set of system design principles that are fundamental and common to both types of systems. Research that identified this architectural pattern and design principles is reported, updated, and applied here in two Parts. Part 1 focuses on agile-systems engineering, reviewing the origins, values, and core concepts that define and enable domain independent agility in any type of system. Part 2 focuses on agile systems-engineering, identifying core agility-enabling concepts in the software-development domain-specific practice known as Scrum, reviewing an agile hardware/software satellite-development systems-engineering case for its source of agility, and then suggesting the development of an agile systems-engineering life cycle model as a natural next step. © 2014 The Authors.