While the study of terrorism has expanded dramatically since the 1970s, most analyses are limited to qualitative case studies or quantitative analyses of international incidents only--which comprise a very small proportion of all terrorist events. Until now, empirical data on both domestic and international terrorist events have not existed. We have compiled information from more than 69,000 terrorism global incidents from 1970 to 1997. Most of these data were originally collected from a private intelligence service agency using open-source data. Since we completed coding the original data in 2005, we have been continually updating and validating the data and we now call the Global Terrorism Database (GTD). We begin this paper by describing the data collection efforts and the strengths and weaknesses of relying on open-source data. We then summarize completed research projects and end by listing on-going efforts to better understand the dynamics of worldwide terrorism events.