This chapter assesses the learning effects of the appliance of ten negotiation simulations across a spectrum of different student cohorts. Based on a typology of learning effects distinguishing between substantive knowledge, skill-building, and affective learning, the chapter analyses to what extent negotiation simulations generates student learning. The student cohorts are comprised of full-time university students (B.Sc. and M.Sc.) and professionals/public managers, who study part-time at the university (Professional Master of Public Management/Governance), as well as a cohort of selected high school students (Academy for Particularly Talented High School Students). The empirical data are based on quantitative data on substantive knowledge and qualitative data on the students’ experience of the negotiation simulations, as well as quantitative data on satisfaction levels via final course evaluations. The analysis reveals that while negotiation simulations undoubtedly stimulate students’ engagement and motivation and – in the students’ own perception – learning, measurable learning effects are more dubious. As opposed to the students’ own very positive statements about learning effects of negotiation simulations, assessable learning effects are harder to catch. There are some effects, but also important biases, as simulations tend to twist student’s perceptions of systems and processes disproportionately towards the issue, institution, or process in question during the particular simulation.