Light rail has been successfully implemented in many urban regions worldwide. Although light rail has been a proven transport concept in many cities, there is much debate on the (societal) cost-benefit ratio of these systems. In addition to the success stories, several light rail projects were not that successful or even failed. In recent years, many light rail plans have been cancelled in The Netherlands, some after many years of planning and some even after the start of the tendering process or during trial operation. We want to know why this happened, so we will be able to support future design and decision making. This paper describes our research aiming at the answer to the question: what are the success and failure factors of light rail planning based on the Dutch experiences? This research has been performed as a survey, in which we investigated five projects, being light rail projects in the Netherlands (and one reference project in France) that either succeeded or failed in different project stages. The main conclusion is that several, multidisciplinary factors make a success or failure out of a light rail project. Projects do not fail just because a lack of funding, small political support or technical obstacles only. Rather than that, a combination of factors causes projects to fail. Subsequently, projects will only be successful if they are based on more than one success factor. Just a high potential ridership or political support is for instance not enough to guarantee a project to succeed.