The dissertation addresses the general question of how social movements interact with the media in contemporary, media-saturated societies. The basic assumption is that visibility in the media is crucial to become recognized and thus valuable social and political subjects. This is especially true for resource-poor groups of activists at the margins of the political field who aim to introduce new social problems into the public arena. Compared to past decades, however, visibility today holds a different meaning, and passes through different channels due to the emergence of information and communication technologies which have transformed mainstream-dominated media systems into more nuanced and complex media environments. The dissertation is based on an interdisciplinary analysis about how social and political actors involved ingrassroots mobilizations against insecure employment in Italy and Europe seek visibility at the public level by acting in complex, multilayered media environments. In doing so, the dissertation presents three relevant novelties in two strands of literature: social movements studies and communication/media studies. At first, the analysis revolves around the concept of activist media practices and three important dimensions that emerged from the investigation: media representation of activists and mobilizations; activists’ perceptions of the media environment; and interactions between social movements and the media. The former and the latter have been addressed in the literature, but separately and without comparing how they develop with regard to different types of media outlets. Scholars in the field, moreover, do not usually consider activists’ perceptions of the media environment, despite the relevance this dimension has for understanding activist media practices. Second, the analysis is based on a comparative research design which takes into consideration three territorial levels (transnational, national and local), three types of media outlets (mainstream, sympathetic and alternative, with the second never having been empirically explored in studies about social movements and the media), and a number of media technologies (from the press to the Internet). The dissertation compares a broad range of (activist) media practices which the existing literature in the field considers separately, while in reality they develop in parallel and often intertwine. Third, the empirical research on which the dissertation is based deals with a critical area of investigation, the realm of insecure and precarious jobs. Despite the fact that this issue has already been addressed by several disciplines, including the sociology of work and industrial relations, there is only a sporadic and fragmented body of literature about mobilizations of precarious workers in Italy and Europe. After a theoretical and methodological introduction, the dissertation empirically explores the three above-mentioned dimensions of activist media practices in complex media environments. Conclusions recompose the three dimensions of activist media practices (representation, perception and recognition) in complex media environments, taking into consideration the literature on the sociology of practices and insights from two relevant theoretical approaches: field theory and actor network theory. Additionally, the conclusions discuss the empirical and theoretical validity of three relevant concepts in the field of media and social movements: 'sympathetic media', the 'discursive opportunity structure' and the 'communication repertoire'.