This study formulates a conception of knowledge in interactive practice disciplines such as education and health care and clarifies different types of knowledge in these disciplines. Focus is on the relationship between practical and theoretical knowledge. Four theses are discussed: (1) the role of knowledge in an interactive practice is to guide practice; (2) different types of knowledge in an interactive practice consist of value-knowledge, factual knowledge and procedural knowledge, parts of which are unarticulated, parts articulated; (3) science is a way of articulating and creating knowledge that can be used as internal action determinants in the practice concerned; and (4) theories in an interactive practice can have both a theoretical and a practical purpose but the theoretical purpose is also indirectly linked to the practical. (Author/JD)