Accessing higher education without having to overcome bureaucratic hurdles is a serious concern for refugees. Although empirical studies on the integration and success of refugees in higher education are scarce, the challenges related to this issue are becoming apparent. The Success and Opportunities for Refugees in Higher Education (SUCCESS) research project has been launched to investigate the effectiveness of new online study programs offered on the Kiron Open Higher Education (Kiron) platform that provides refugees with access to Massive Open Online Courses (MOOCs). SUCCESS measures the prior knowledge and skills of refugee students and investigates to what extent their study opportunities, learning processes, and chances of academic success can be improved effectively through different forms of support provided in Kiron. In this paper, we present the assessment framework and study design of the SUCCESS project as well as data on 1,376 students entering the study program in Kiron in summer 2017. As students' language skills, intellectual abilities, and prior study-related knowledge play a significant role in their performance in higher education degree programs, we focus on the crucial introductory study phase and valid diagnostics of students' study preconditions. We analyze refugee students' sociobiographical and educational data such as gender, country of origin, highest level of education achieved etc. and examine their English language skills, intellectual abilities, and previous study domain related knowledge. We find extreme differences in levels of education and preconditions on starting to study in Kiron. Based on these results, we discuss implications for the effective and successful integration of refugee students in higher education.