Constructivist research in Science and Technology Studies is committed to revealing the heterogeneity of technological change and the fluid boundaries between the elements involved. Its major theories, the Social Construction of Technology and Actor Network Theory, have however both been criticized for limiting themselves to the micro-level of cases, impeding a structural analysis of technological systems. This article seeks to bridge any such divides. We research the recent changes in the viticulture of Mendoza, Argentina, which underwent radical changes over the (...) past decades: once governed by low-cost yield maximization, grape production now revolves around “quality.” To show how the particular quality definition developed, we depart from a social-constructivist framework, following the sociotechnical shaping of problem-solution relationships across the wine production system. To include relevant social groups from different settings around the world, we gradually incorporate the ANT concepts of obligatory passage points, enrollment, convergence, delegation, and codes into the analysis. Combined into the concept of “sociotechnical alliance,” our analysis follows the dual process of creating agreement while establishing heterogeneous practices across settings at different levels. It shows that functioning involves alliance building and highlights the hybridity and continuous dynamics of systems at large. (shrink)