The ISSP Religion module consists of three surveys from 1991, 1998 and 2008. The 2008 survey is a partial replication of the 1998 study and the 1998 survey a partial replication of the 1991 study.  

The ISSP Religion module mainly deals with religious beliefs, religious socialisation, past and current religious practices, religion and governmental connections, religion in comparison to other aspects, and secular aspects.