This working paper describes the expert interviews within the research project SEO-Effekt. To incorporate the perspective of experts from fields related to search engine optimization (SEO), we conducted interviews with three groups: search engine optimizers, content managers, and online journalists. On the one hand, we asked questions about which indicators refer to SEO techniques carried out on a website. On the other hand, the experts provided us with assessments of the relationship between search engine users and SEO. From content managers and online journalists, we also learned how SEO has affected their day-to-day work. The interviewees assume that search engine users have very little SEO knowledge, misjudge the impact of SEO, and that their perspectives on SEO differ in terms of their sector, their level of education, and their interest in search engines. From the assumptions about the users we will generate hypotheses for a representative online survey. The SEO indicators will be used in the development of software for automatic analysis of search results.