Recent debates on learning have shifted the analytical focus from formal organizational arrangements to informal personal ties. Personal knowledge networks, though, mostly are perceived as homogenous, cohesive, and local personal ties. Moreover, a functionalist tone seems to prevail in accounts in which personal knowledge networks are seen to compensate the shortcomings of the formal organization. This paper sets out to expand the dominant construal of networks, which is largely molded by the notion of embeddedness. Against the background of in-depth empirical analysis of the project ecologies of the Hamburg advertising and the Munich software business, the paper will first venture into the neglected sphere of thin, ephemeral, and global personal knowledge networks by differentiating between connectivity, sociality, and communality networks. Second, the paper not only elucidates the supportive functions of these ties but also explores the tensions between personal interests, project goals, and the firm's aims that are induced by these personal knowledge networks.