Shrinking lot sizes and growing product variability demand frequent changes in manufacturing systems. Common manufacturing systems, however, are built for large, invariant lot sizes. (Self-)adaptive manufacturing systems can, on the other hand, react quickly to changes in both function and capabilities. This ability makes them suitable to meet new customer or production requirements. Introducing (self-)adaptiveness in manufacturing requires designing adaptable and flexible systems and anticipating runtime changes at design time. In this article, we describe the engineering of (self-)adaptiveness of manufacturing systems by presenting definitions, significant challenges, and promising solution approaches. We limit the scope of work on designing and realizing such manufacturing systems based on reference architectures, self-organization, and knowledge-based reconfiguration.