This article discusses characteristics and forms of international collaborative research projects (ICRPs) and provides conceptual considerations as well as initial empirical insights on the impact of funding conditions on ICRPs in the social sciences and external project funding. Specifically, by presenting a German case study of funding formats in two national funding institutions and the funding tools of the European Commission in Horizon 2020. The findings draw on desk-research and a review of research on the relationship between funding and international research collaboration. The analysis used a conceptual perspective, that understands research projects as temporary organisations, to discuss characteristics of international collaborative research projects and to provide a descriptive analysis of the funding conditions for ICRPs. The article systematises different forms of ICRPs and suggest differentiating them along their variety by four ICRP attributes: size, geographical distance, funding structures and funding formats. The discussion section elaborates on implications for future research and practice?.