In the modern, fast-paced world we inhabit, companies cannot afford to be lethargic. To keep up with the competition, they have to continually change, evolve, and even reinvent themselves over time. We cannot ignore this fact when designing systems, especially if we intend to design software that’s well adapted to the requirements of its business domain. When changes are not managed properly, even the most sophistica‐ ted and thoughtful design will eventually become a nightmare to maintain and evolve. This chapter discusses how changes in a software project’s environment can affect design decisions and how to evolve the design accordingly. We will examine the four most common vectors of change: business domain, organizational structure, domain knowledge, and growth.