The aim of this study will be to test the efficacy of a Transdiagnostic Internet-based protocol (Emotion Regulation Protocol) for the treatment of emotional disorders by means of a randomized controlled trial in a sample made up of participants from specialized care of the Spanish public mental health system. The study will include two conditions: a) Transdiagnostic Internet-based treatment protocol and b) TAU. The main hypothesis is that the Transdiagnostic protocol will be more efficacious than TAU and that will obtain a good acceptance by patients and mental health professionals. We also expect the online Transdiagnostic protocol to be more efficient when compared with TAU (e. g., a significant greater number of patients which receive a psychological treatment, a significant reduction of the waiting lists and costs such as hours of clinical assistance and hours of face-to-face treatment, etc.).