The aim of this study was to compare two ways of administrating the complementary psychological support (scheduled vs. non-scheduled) in an online self-help program for panic disorder. In order to do so, the investigators studied: a) If there were differences in the intensity and frequency of the symptoms of panic disorder. b) If there were differences in the therapeutic adherence between the subjects receiving both kinds of complementary support. c) If the more time spent by a psychologist in therapeutic interventions produced the best results of therapeutic adherence / symptom improvement.