Why do investors choose investor-state dispute settlement (ISDS) to resolve investment disputes with foreign governments even though it is an uncertain, lengthy, and expensive process, that is potentially detrimental to the relationship with the host government? This thesis provides an empirical answer to that question. It examines 28 ISDS claims that are analysed in 16 Qualitative Comparative Analyses (QCAs). It finds that the vast majority of filed ISDS claims can be explained by having had access to funds to file a claim and perceiving the host government as reluctant. Sufficient funds in combination with either a willingness to discontinue the relationship with the host government or a strong case were also able to explain a number of instances. Based on these results, the thesis advocates for mandatory mediation prior to filing ISDS claims in order to mitigate the perception that the host is reluctant and discourage investors to leave the host country.