The study examines the effectiveness of a computer-based self-help-program for individuals with problematic and 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. The primary outcome is the PG-Y-BOCS as a measure of the severity of pathological gambling symptoms. Secondary outcomes are rates of depression, measured with the PHQ-9 as well as gambling-specific cognitive biases, measured with the GABS. The program is expected to lead to a significant reduction in problematic/pathological gambling behavior (PG-Y-BOCS) and also to declines in both depressive symptoms (PHQ-9) and gambling-specific cognitive biases (GABS). The study is conducted as a radomized-controlled trial with one intervention group and one wait-list control group. The intervention group receives the login data directly following the baseline survey and can use the program over a period of 8 weeks, whereas the wait-list control group receives access to the program after completion of the post-survey.