Everything is designed. From the fork you hold in your hand, to the car you drive, to the public transportation you use, to the mechanisms for justice within a society, to the process of designing itself. Embedded in these designs are the assumptions that underlie the design methods and toolkits used in the design process. In practice, design happens through the application of methods (processes that result in design outcomes), toolkits (materials that support the implementation of methods), and heuristics (the skillful application of methods and toolkits) (Friedman & Hendry, 2019; Hendry, Friedman & Ballard, 2021; Nelson & Stolterman, 2012). Methods and toolkits originate within particular worldviews (Ansari, 2019) and carry with them the assumptions of those worldviews. For example, journey maps, a design method that originated and is used in industry, assume linear time and often ignore the material aspects of the experience at hand. Conversely, traditional methods for making coconut milk developed in Papua New Guinea, outside the dominant Western interpretations of time, allow for spending time together but take longer to enact (Wajcman, 2015). But there are always different ways of doing things, different worldviews, and different assumptions to bring to bear in a design situation. Designers can bring those different assumptions into a design situation by adapting design methods to account for new theoretical constructs. But in what ways does theory inform design methods and toolkits? How can this relationship be modeled? Can a model of the relationship between theory and design methods and toolkits be used to help translate specific theoretical constructs into established design methods and toolkits? If so, then could this model and the associated skills be taught to novice designers as they adapt design methods? In this dissertation, to gain traction on these questions, I begin by developing a bi-directional model of knowledge types -- know-about, know-that, know-how -- in design to describe how theory informs design practice and vice versa. While the model of knowledge types in design is bi-directional, to contain the scope of this dissertation I focus the remaining work on only one direction: from theory to practice. To demonstrate how the model of knowledge types in design could be used to guide the adaptation of design methods, I apply it to eight theoretical constructs (four about materiality and four about temporality) to translate theory-to-practice commitments for each construct and then use those commitments to adapt one established method, journey maps, and one established toolkit, Envisioning Cards. Then, I report on a brief educational case study, demonstrating how novice designers can use the model to adapt established design methods. Then, drawing on the above, I offer heuristics to guide others as they adapt design methods and toolkits. Finally, I reflect on the work of adapting design methods and toolkits as a design process and the flexibility of design methods and toolkits as a lever for incorporating theoretical constructs into design practice. This dissertation makes the following contributions: 1) a bi-directional model of knowledge types in design to describe how theory can inform design practice and vice versa; 2) one adapted design method; 3) one adapted design toolkit; 4) an educational case study exploring the use of the model of knowledge types in design as a tool for teaching method adaptation; and 5) heuristics that novice designers, design researchers, and practitioners can use to adapt other design methods and toolkits. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]