The task of this paper is to ground the notion of cyberethics of co-operation. The evolution of modern society has resulted in a shift from industrial society towards informational capitalism. This transformation is a multidimensional shift that affects all aspects of society. Hence also the ethical system of society is penetrated by the emergence of the knowledge society and ethical guidelines for the information age are needed. Ethical issues and conflicts in the knowledge society are connected to topics of ecological and social sustainability. For information ethics and cyberethics, the sustainable design of society, social, and socio-technological systems is important. In this context the notions of sustainability and co-operation are discussed. Based on these categories, the approach of cyberethics of co-operation can be theoretically grounded.