The study examines the effectiveness of a computer-based self-help-program for individuals with problematic or pathological gambling behavior.The main objective of the study is to investigate the extent to which the online program leads to a significant reduction in pathological gambling (prirmary outcome), depression and gambling-specific dysfunctional thoughts. The program is expected to lead to a significant reduction regarding all measures when compared to a control group. The study is conducted as a radomized-controlled trial with one intervention group and one wait-list control group.