Researchers have approached the problem of designing context-aware systems, computer systems that can react intelligently to the context in which they are used, from both software engineering and human-centred perspectives. While engineered context-aware systems have found successful application in optimising technical settings without requiring mundane and explicit interaction from humans, challenges remain in furthering their application to more complex environments. In particular, when technical decisions and human actions are intertwined in sophisticated work environments (rather than, for example, the simple act of transferring a mobile phone call to receive a signal from the nearest tower), the problem of designing context-aware systems demands further examination and calls for a new approach. A natural extension of the software engineering approach in more challenging environments is to try to implement increasingly sophisticated algorithms for managing context in the hope that this will lead to autonomous application behaviour. In contrast, research from a human-centred perspective, grounded in the social sciences and philosophy, demonstrates that context is not entirely objective and measurable but rather is dynamic and created through human action. It may not be easily detected through technical sensing systems, and therefore simply employing more sophisticated algorithms within the technical sphere may not be effective. While engineering approaches have continued to evolve, the problem of how to design interfaces to context-aware applications still remains. The research reported in this dissertation investigated the problem of designing context-aware systems for the complex environment of a dental surgery. I undertook, though a participatory design approach (a) to better characterise the problem of designing context-aware systems, and (b) to understand how design methods could be employed to bridge the human and software engineering approaches. The gap in existing research on context-aware systems is evident in the way that the methods applied to designing systems don't provide an insight into how people actively create the context in which they work (in a practical rather than theoretical sense) they don‘t closely examine the behaviours of people, the role and arrangement of artefacts, and the dynamic relationships between people and artefacts. I found that an understanding of how these features of work and human behaviour are realised in practice in a given environment is fundamental to being able to design an effective context-aware system for that environment. The challenge is to design at the boundary between the technical and the social. The contribution of this thesis is an approach that explores context-aware design through synthesis. The synthetic approach leads to design opportunities and guidelines based on an understanding of the processes through which people actively co-create the context in which they work. I have applied and built upon a number of existing user-centred design and participatory design methods, in addition to creating some new methods in order to develop an understanding of how designers can examine the human aspects surrounding the co-creation of context and apply these in a way that progressively informs the design process. The methods collectively represent a novel approach to designing context-aware applications and differ from the more traditional technical approaches of developing software frameworks and infrastructures, and formal models of context, tasks, users, and systems. The techniques presented have focused primarily on developing an understanding of how humans find meaning in their actions along with their interaction with other people and technology. Participatory design methods help participants to reveal potential implicit technical resources that can be presented explicitly in technologies in order to assist humans in managing their interactions with and amidst technical systems gracefully. The methods introduced and the design approach proposed complement existing research on context-awareness from both a human-centred and software engineering perspective. This research builds on the notion of providing resources which allow users to manage their own context and also manage shifts in control while interacting with other people and with a variety of technical artefacts. It does this by examining a complex work environment, in particular looking at the kinds of resources people use and expect to use (and the constraints around these), the form(s) it is appropriate for them to take, and the patterns of interaction they will ultimately be used within.