The convergence of mobile technologies, media, and the Internet is transforming the way that digital content is produced, distributed, and consumed, especially among children and young adults. In Europe as in many other areas, minors are exposed to an ever-growing amount of digital content on mobile phones, tablets, or computer screens. Increasing exposure at an early age brings both new opportunities and risks. This paper reviews the current discussion about strategies that deal with inappropriate, harmful, and illegal content online and proposes a particular co-regulatory, technology-driven approach based on the active involvement of children, their families, and the educational system. The MediaKids project aims to test this coregulatory approach by developing a mobile application-the MediaKids app-within the broader context of an educational programme to raise awareness about online safety. The project seeks to involve children and young adults in defining the notion of "harmful content" and, ultimately, in the elaboration of the policies for the emergent digital public space.