Science and technology studies concerned with the study of lay influence on the sciences usually analyze either the political or the normative epistemological consequences of lay interference. Here I frame the relation between patients, knowledge, and the sciences by opening up the question: How can we articulate the knowledge that patients develop and use in their daily lives and make it transferable and useful to others, or, `turn it into science’? Elsewhere, patient knowledge is analyzed either as essentially different from (...) or similar to medical knowledge. The category of experiential knowledge is vague and is used to encompass many types of experience, whereas the knowledge of the `expert patient’ may be assumed to have the shape of up-to-date medical information. This paper shows through a case study of people with severe lung disease that patient knowledge can be understood as a form of practical knowledge that patients use to translate medical and technical knowledge into something useful to their daily life with disease. Patients coordinate this with homegrown know-how and advice from fellow patients, weighing different values - of which `taking good care of one’s body’ is but one - that may conflict in a specific situation. These practices result in sets of techniques that may be made useful to others. The paper argues for two alternatives to state-of-the-art medical research to turn patient knowledge into science: ethnographies of knowledge practices and the collection and making accessible of techniques. (shrink)