This document announces and provides information about the Hacks4Democracy hackday event on open government, open data, and transparency to be held on April 17-18, 2010 in Berlin. It discusses why open data and transparency are important for democracy and decision making. The hackday aims to explore open government data, build applications and prototypes, and demonstrate what can be done with publicly available data. An agenda is provided outlining presentations and sessions for hacking, as well as guidelines for participants to prepare short introductions about their hack projects. The document concludes by stating this is just the beginning of open government events.