Nowadays, interest in the emerging field of disaster psychology has increased significantly after events such as September 1, 2001 in New York, March 11, 2004 in Madrid, or December 26, 2004 tsunami in Asia. Also this interest has been centred in the need to treat rape, assault or other crime or accident victims. The present article shows a revision of the main early psychological approaches and interventions in the immediate response to disaster. Psychological First Aid (PFA) is defined as a group of short, practical and early psychological interventions oriented to relieve and prevent the psychological effects of traumatic events in the short, middle or long term. PFA is useful to offer psychological support in the medium or moderate stressful life events as well as in great intensity ones. The main objectives of PFA are the person emotional stabilization, their connection with the natural social support networks and the decision of the derivation to mental health services. The basic principles and the protocols of PFA are revised and their common characteristics are summarised. Finally, a PFA practical action guide developed and applied in different disasters, war and terrorism settings by the authors is presented (ACERCARSE protocol).