The International Social Survey Programme (ISSP) a cross-national collaboration programme established in 1984. It is a continuous program conducting annual surveys on diverse topics relevant to social sciences. ISSP brings together pre-existing social science projects and coordinates research goals, thereby adding a cross-national, cross-cultural perspective to the individual national studies. Research activities are carried out continuously in annual cycles. Successive surveys are always partial replications of earlier surveys. The Czech survey within Religion module has been conducted three times since the existence of the ISSP: 1998, 2008 and 2018. Successive surveys are always partial replications of earlier surveys. ISSP Religion modules focus on religious attitudes and beliefs, religious socialization, past and current religious practices, religion and governmental connections and aspects of secularization.