Social trust is understood in social sciences as a key component for social cohesion, economic growth and political development of a society, as it is the “glue of social life”. Immigration caused by the economic miracles after World War II and by refugees from crisis areas generated a growing religious an ethnic divsersity in Western societies. The plurality of origins, denominations and cultures that increasingly form part of our society is frequently assumed to undermine social trust in current modern societies (Putnam). The purpose of this paper is to decompose for the first time empirically the impact of different factors that are assumed to be determinants of trust and distrust by using a factorial survey. This experimantal design carried out among students from Bilbao and Cologne consists in judging variing descriptions (vignettes) of fictitious persons acting in an from the researcher in advance defined situation. By using mulilevel analyses the implact of the described characters of the ficitious persons as well as the impact of respondent characteristics on trust can be estimated simultaneously. Besides that it also allows to answer the question of whether trust is higher a) among people that share the same characteristics and b) in denominational comparably more mixed Cologne than in denominatinal rather homogenious Bilbao.