New movements in project management are pushing project teams to hunt down contacts well outside their regular networks, to tackle problems encountered throughout project rollout. This raises the issue of initiating cooperation with someone unknown—that is, harnessing weak ties to tap into resources well outside the comfort zone. Our investigations into polar expedition projects has led us to develop the notion of a potentially cooperative weak tie, converging Granovetter's approach with a synthesis about cooperation differentiating identity-sense and utilitarian mechanisms. We conclude that a weak tie can initiate a cooperation only if it includes one of these two sources of cooperation.