Monllor, JavierPavez, IgnacioPareti, Stefania2021-09-012021-09-012020Disaster Prevention and Management 2020, Vol. 29 No. 4, pp. 575-589https://doi.org/10.1108/DPM-05-2019-0151http://hdl.handle.net/11447/4559Examine and understand how an informal volunteer’s goals and actions develop from the moment they first learn about a disaster. We examine informal volunteerism (the activities of people who work outside of formal emergency and disaster management arrangements) through the theoretical lens of entrepreneurial effectuation to explain informal volunteer behavior and cognition and gain insight on how they develop their disaster relief ventures. We find that informal volunteers follow an effectual logic, relying on available means to take advantage of opportunities as they are recognized or created. Application of effectuation vs causation processes depended on whether the informal volunteers were categorized as traditional, emergent or extended volunteers. Informal volunteers’ disregard for the Affordable Loss Principle task governments and disaster relief organizations with the important challenge of managing and assuring the safety and well-being of informal volunteers. Their entrepreneurial behavior also invites the establishment of formal processes to counsel and guide informal volunteers, helping them fill out the necessary paperwork and funding applications to develop their efforts. Through their experimentation and flexibility, informal volunteers accelerate disaster recovery, recognizing opportunities, working around bureaucracy and other roadblocks that hinder the efforts of established organizations. They also demonstrate entrepreneurial behavior that helps revitalize and jumpstart the local economy, making for stronger and more resilient communities. This study borrows from Effectuation Theory from the entrepreneurship field in order to bring a much needed theoretical lens to the topic and greatly assists informal volunteerism research, moving from past efforts that simply define and categorize the concept.22 p.enDisaster reliefEntrepreneurshipInformal VolunteerEffectuationCase studyOpportunity RecognitionDisaster response and recoveryDisasterArticle