The emergence of practice-centered computing (e.g., Computer-Supported Cooperative Work, or CSCW) raises the crucial question: How can we conceptualize the practices into which the prospective technology is to be integrated? How can we, reasonably, say of two observed activities or events that they are, or are not, instances of the same type? These are crucial questions. This chapter therefore attempts to clarify the concepts of “practice” and “technique.” First, since our ordinary concepts of “practice” and “technique” developed as part of the evolution of modern technology, as tools for practitioners’ and scholars’ reflections on the role of technical knowledge in work, the chapter outlines the major turning points in the evolution of these concepts, from Aristotle (via the scholastics), to enlightenment thinkers such as Diderot and Kant, and finally to Marx and Marxism. The chapter thereafter moves on to analyze the concepts as we use them today in ordinary discourse.