This year's discovery challenge presents two tasks in the new area of social bookmarking. One task covers spam detection and the other covers tag recommendations. As we are hosting the social bookmark and publication sharing system BibSonomy, we are able to provide a dataset of BibSonomy for the challenge. A training dataset for both tasks is provided at the beginning of the competition. The test dataset will be released 48 hours before the final deadline. Due to a very tight schedule we cannot grant any deadline extension. The presentation of the results will take place at the ECML/PKDD workshop where the top teams are invited to present their approaches and results.