There has been an ongoing conversation about the role and relationship of theory and practice in the HCI community. This paper explores this relationship through a tentative model, which describes a “trickle-down” of theory into practice, and a “bubble-up” of ideas from practice to inform research and theory development. Interviews were conducted with interaction designers, which included their knowledge of two design methods—affinity diagramming and the concept of affordance—as well as a description of their use of design methods in practice. Based on these interviews, potential relationships between theory and practice were explored through this model. Knowledge of the history or key steps of executing a design method was not found to negatively affect the ability of a designer to apply the key concepts of a method in practice. Opportunities for future research, based on the use of the tentative model as a generative model, are considered.