This data set contains the data used for the analysis of the research article “Boosting Survey Response Rates by Announcing Undefined Lottery Prizes in Invitation Email Subject Lines: Evidence from a Global Randomized Controlled Trial”. It comprises data from a randomized, controlled trial using a multicultural, multinational sample of 5,128 key staff members working for 2,527 microfinance institutions (MFIs) located in 124 countries; as well as all control variables used in the analysis included in the paper and its online appendix (e.g., location of an MFI in a country that is a member of the Organization of Islamic Cooperation, and two culture scores constructed by Beugelsdijk and Welzel, 2018, using data from the European Value Studies and World Values Surveys). Primary data was collected by means of a personalized invitation email, which included a link to an online survey. The online survey was conducted in 10 languages including English and ran from April to June 2016.