Social norms as concepts of legitimate and appropriate action are basic elements of social coordination and essentially “communication phenomena” (Rimal & Lapinski, 2015, Lapinski & Rimal, 2005). They are negotiated, shaped, understood, learned, and maintained through communication, with mediated public discourses as central forums for the communication and negotiation of norms. Despite this importance, studies on the construction of norms in mediated public discourses remained a research desideratum. This lack of research is even more pronounced for how actors envision and construct norms for the use of digital technologies and visual data practices in our connective and highly mediatized, visualized, and datafied world. The cumulative dissertation addresses this gap and extends research on norms on the conceptual, empirical, and methodological level. It examines the construction of norms in mediated public discourses for a highly topical area of application – visual data practices – in three individual articles. The studies examine how actors evaluate, legitimize, or contest visual data practices, how they discuss their social and political implications, and how they thereby envision and construct norms for visual data practices. Study 1 provides qualitative in-depth insights into event-related discourses on norms for visual data practices in a specific national context. Based on a qualitative content analysis of newspaper articles, tweets, experts’ reports, minutes of parliamentary debates, and committee hearings, the study examines legitimizations and contestations of visual data practices after the 2017 G20 summit in Hamburg. Study 2 analyzes the construction of norms in a quantitative comparative research design. The study examines frames and the construction of norms in news media discourse on facial recognition tools in Germany, Ireland, Italy, Switzerland, and the UK and is based on a quantitative content analysis of 2195 print and online news articles published in 15 high-circulation newspapers between 2013-2019. Whilst study 1 and study 2 particularly help with the examination of the construction of norms on the verbal level ; study 3 further expands on the role of visuals and the multimodal interplay in the construction of norms in mediated public discourses. The methodological article presents an analytical framework for a qualitative content analysis of norms that allows for the identification of mode-specific contributions, as well as interplays of images and verbal text. Overall, the dissertation (1) provides a novel and interdisciplinary perspective on norms that focuses on the hitherto understudied discursive dimension of norms as communication phenomena ; (2) advances qualitative and quantitative methods to analyze norms ; (3) examines the construction of norms in mediated public discourses for a highly topical area of application ; i.e. visual data practices ; and (4) shows empirically how actors publicly envision and construct norms for visual data practices and what practices actors deem appropriate or inappropriate, and for which reasons. As such, the dissertation shows how norms for urgent social concerns in nowadays societies, such as balancing privacy and security, are discussed and constructed in mediated public discourses. Results show that privacy, data sovereignty, and security or efficiency are mainly characterized as antagonistic and incompatible goals and principles.