This article offers three interrelated arguments for the adoption of a cultural approach to the study of learning. It then presents some early analyses of data from a case study of one learning site, concerned with the assessment of learning in the workplace. These analyses show how the shape of the learning site--for example, the nature of learning, the extent of opportunities for learning--is partly a product of the playing out of tutor disposition in relation to a field. Specifically, it is suggested that the absence of alignment between tutor disposition and the field within which her practices are located has resulted in "underground learning," beyond the gaze of college processes. At the same time, all parties are dependent upon the success that is the end result of this underground learning. This scenario, in turn, presents difficulties for any conventional notion of "improvement," and the discussion illustrates the power and the utility of a cultural approach for a deeper understanding of learning, with implications for both practice and policy. (Contains 2 notes.)