The field of psychology has entered an exciting period. In fact, one can argue that it recently took one of its most significant steps since it emerged as an academic discipline nearly a century and a half ago. It will be explained in Chapter 1 how psychology recently became a unified, paradigmatic science that is now fully consistent with the rest of the natural sciences. For the first time in its history, psychology can now be considered one of the natural sciences. This is an historic achievement that also increases the potential of the field to strengthen its effectiveness as a health care profession. This likewise strengthens the potential of the field to help improve the behavioral health of the population in general.