Despite the socio-political importance that occupational pension schemes have had since 2001, the incomplete evidence, lack of transparency, and lack of databases have been criticized regularly during the last 20 years.   The aim of this project is to take stock of the research and the databases currently available. We want to find out what we already know about the occupational pension system and about the data on which this knowledge is based. Only with this information, it is possible to identify the need for future research and the data sources required for this. For example, we are investigating which data would be necessary in order to be able to estimate reliably the contribution that the occupational pension system has made in closing the pension gap. In addition, only with the right data and appropriate evaluations it is possible to have a sound discussion about the cost efficiency and performance of the occupational pension system.   We proceed in three steps. First, current research results relating to the occupational pensions are collected. The focus will be on research results concerning the distribution and the amount of entitlements in Germany. Second, we compile the existing data sources in Germany and identify any gaps. Third, reference is made to countries such as the USA, Denmark, the Netherlands and Great Britain, as these countries have a long history of occupational pension schemes. The experiences from the international literature serve as reference points and provide further insights.