Volunteering is one of the most significant trends in social activity today. Numerous emergency situations (hereinafter referred to as ES), both natural and man-made, lead to human casualties, negative consequences for nature and infrastructure, and volunteers, despite the existing risks for their life and health, provide significant assistance in preventing these situations or combating their consequences. This activity, in turn, actualises the study of the reasons why people get involved in voluntary, unpaid work, and carry it on for a long time. The investigation of the motives of volunteers' participation in emergencies, presented in this article, is carried out using the “grounded theory” method by A. Strause and D. Corbin. The analysis is based on data from 45 semi-structured interviews with volunteers operating in ES (search for missing people, rescue work, first aid and humanitarian aid, etc.), and experts in the field, namely, heads of public organisations and professional rescuers. The study describes a set of stimuli that motivate people to volunteer in an emergency. As the analysis of interviews has shown, the fundamental category of participation in ES is helping other people, and it is explained through such motives as altruistic, personal, social, career and protective. At the same time, the identified motives almost completely intersect with the typology of motives identified in the study by I. Clery. The above study showed that most often volunteers in ES had personal motives (volunteering in ES as self-development), and most rarely career ones (becoming a professional rescuer through volunteering in ES). When the need arises, volunteers "help" physically, as far as their health allows, and as far as the state rescue services allow. Among the benefits of volunteering in ES, the respondents name “a sense of satisfaction”, thanks to it, volunteers want to continue their activities. The results of the study show that volunteering in an emergency is a process leading both to an increase in the effectiveness of prevention / elimination of the consequences of an ES, as well as to the development of the volunteers personality in various spheres: emotional, personal, and career.