***Apologies for cross-posting.*** Dear colleagues, please find attached the call for submissions of the Open Probability-based Panel Alliance (OPPA, http://www.openpanelalliance.org/ ). OPPA consists of four probability-based panels: the GESIS Panel in Germany<https://www.gesis.org/en/gesis-panel/gesis-panel-home/>, the LISS Panel in the Netherlands<https://www.lissdata.nl/>, the Korean Academic Multimode Open Survey (KAMOS) in South Korea<http://cnukamos.com/eng/main/index.php>, and the Understanding America Study (UAS) in the USA<https://uasdata.usc.edu/index.php>. The Alliance facilitates cross-cultural survey research with probability-based panels across the globe, endorsing joint methodological standards to yield representative data. In order to showcase the alliance, we would like to invite you to submit your study proposal and collect your own data within OPPA free of charge! Deadline for submission is 17 June 2018. We look forward to your submissions! Bernd Weiss -- Dr. Bernd Weiß GESIS - Leibniz Institute for the Social Sciences Survey Design and Methodology | Team GESIS Panel Head of the GESIS Panel P.O. Box 12 21 55 | 68072 Mannheim | Germany Phone +49 621 1246 557 | Fax +49 621 1246 577 http://www.gesis.org<http://www.gesis.org/> | http://berndweiss.net/