This textbook is an introduction to Logistic Regression statistical model illustrated by and example on revolving credit. The research was supported on a database consisting by payment behavior of 4 000 credit cards users and their characteristics, being 2000 good and 2000 bad accounts. 80% of the sample was used as in-sample to determine the parameters of the model and the hold-out- sample was used to confirm the robustness of the model. The book is a practical guide for those wanting to use it as reference for academic purposes as well as to credit scoring experts.