The subject of Bulgaria and Romania’s accession to the Schengen area has become a prominent topic in the media in two countries in the last year, due to the constant opposition of Austria, despite the compliance of the countries with the criteria to join the free circulation area. The topic has given birth to a series of misleading narratives (from mild disinformation narratives to full fledged conspiracy theories), especially in the extreme right wing parties’ discourses and alternative media, but also in public discourse of various political actors. In this context, as part of BROD EDMO hub’s research agenda, we plan to analyse the most prominent disinformation narratives about NATO in the two countries covered by BROD and their potential effects of fostering Eurosceptic feelings. In a first step we will conduct an automated content analysis of Facebook public posts (using CrowdTangle) and online media listening in both countries (using Sensika in Bulgaria and Zelist in Romania). We will perform network and cluster analysis to map the most viral disinformation stories about the Schengen area accession topic, and a qualitative analysis of the most prominent disinformation narratives in both countries, with a focus on the cognitive components of disinformation. In a second step, we plan to test effects of such narratives on people’s further engagement with the topic and increase of Eurosceptic attitudes by means of a comparative 3×2 in between experimental design, manipulating the source (social media vs. mainstream media vs. alternative media) and the facticity of the content (accurate facts vs. disinformation). We will use the most prominent stories identified in the automated content analysis to construct the stimuli, conceived as online newspaper posts and social media posts. We expect to find effects of increased Eurosceptic attitudes and increased engagement with the posts after exposure to disinformation content.