Chapter 3 expands our journey beyond the enactment of design participation. The last three decades have witnessed suites of design approaches, both in research and practice that are premised on continuing collaborative design after implementation, resulting in design-in-use approaches such as co-realization, meta-design, and aging together. The rise of hacking and making has, in turn, led to open design initiatives, designing with and for maker communities, peer-content creation, and crowdsourced design and innovation strategies. Furthermore, further design has been being carried out by people using the products and services. The minimum-viable-product development strategies have underscored the benefits and gained versatility of extending the design into the use time. The constraints of and possibilities opened up by situated use are simply difficult to anticipate during concept design. In all these research and practice approaches, the key underlying questions are what and how are people capable of engaging with designs during use time and how is their design engagement supported and built upon. In this chapter, we first go through what different disciplines have established about users’ design engagements during use time. We then present a taxonomy of active use that reveals the impressive range in which active-use phenomena happens. Use as is, active use, locally new designs, and globally new innovations mark different intensities of engagement. These can concern the material form of design, new uses, new meanings, and adjustment to local settings. Equally, there are collective forms of active use that shape communities and organizations, ideologies and imaginaries, and global platforms that facilitate active use. All these aspects and gradations of user engagement can be found in hotspots such as digital-physical making activities, but many also in other digital and physical settings. The chapter then proceeds to elaborate on how the design spaces can be temporally extended using the users’ active design engagement through aging together design guideposts. The aging together methodology is illustrated with a case study of building an information infrastructure for a communal housing initiative with the Active Seniors association, a case that outlines how designs can evolve and blend with infrastructuring and maintenance of community resources.