The article re-reads what has been published in the years 1998-2007 by Sociologia del lavoro through the "lens" of knowlege and knowing-in-practice. It aims to make visible the "traces" left in the Journal by the debate on knowledge, knowledge workers, and community of practice. In so doing this article will connect the journal to other journals and other articles that gave form to the debate in the same years. In those years knowledge has been conceived and studied both as a resource for the firm and as an activity situated in working practices. The passage from an epistemology of possession, in which knowledge is a "thing" to an epistemology of practice, in which knowledge is a collective knowledgeable activity, changed the way of conceiving technology, work and organization. From being separate entities, technology, work and organization are entangled relationships within a practice.