The 13th Annual European DDI User Conference "EDDI21" will be held as a virtual meeting from November 30th to December 1st, 2021. EDDI21 is organized jointly by Center for Socio-Political Data (CDSP), GESIS Leibniz Institute for the Social Sciences, and International Data Service Center at the Institute for the Study of Labor (IDSC of IZA). The DDI Alliance kindly supports EDDI21. Presentations, talks, papers, posters on all things DDI are welcomed: Case studies, mature implementations, early Implementations, interplay of DDI with other standards or technologies, projects in early phases in which DDI is under consideration, critiques of DDI. Online submission system is available June 23rd, 2021. More details are available at: https://www.eddi-conferences.eu/eddi-2021/.