Over the past 30 years, major economic reforms have deeply impacted the Vietnamese agro-food sector. In this study, we use the concept of “sociotechnical transition” to capture the multiple dimensions of this transformation. We focus in particular on the rapid emergence of the Vietnamese dairy industry. Up to the mid-2000s, the sector had been dominated by smallholder dairy farmers working in close collaboration with private milk processors and public services. This resulted in what we propose to call a "peasant" sociotechnical regime. In the late 2000s, the sector experienced a growing competition from agro-industries and mega farms holding several thousand cows. The role of smallholder producers has decreased and the sector has moved toward medium to large-scale producers. This new “corporate” regime profoundly modified the outcome of the post-socialist "transition". This case-study highlights important issues related to the governance of these rapid changes.