Traditional alpaca production in the High Andes has depended on access to irrigated patches of rangeland called bofedales that offer green forage during dry periods. In 1993, Project Alpaca began a participatory program to improve the production and processing of alpaca wool, introducing, a technical package that included fencing materials to help indigenous herders better conserve bofedal forage and improve alpaca nutrition. Our evaluation of the impacts of fencing revealed several consequences. Although households with access to fenced bofedales showed reduced rates of mortality for young alpaca, a proliferation of fencing quickly began to privatize what had been a common property resource. This led to conflict and concern that some households could be pushed out of the system. Efforts to intensify livestock production in such environments must consider the social dimensions of resource use to avoid unintended consequences of interventions.