Focusing on the case study of the so-called ‘European refugee crisis’ in Greece since 2015, the research highlights new insights into the motivations, experiences, and challenges of international volunteers in humanitarian relief operations. Unlike previous analyses on volunteer motivations, this study’s analytical framework is built on a combination of the functional (psychological) and symbolic (sociological) approach to the theory of motivation. With the help of Clary and Snyder’s Volunteer Functions Inventory, seven motivations of volunteers are outlined. Further, volunteers’ challenges, including psychological stressors are identified with the help of the Maslach Burnout Inventory. Building on a mixed methods research design, 66 responses to an online survey were enriched with data from six in-depth interviews. The study displays volunteers’ typical socio-demographic characteristics to be young, female European students, who come to Greece on their own, who finance their stay through personal income, and who tend to stay between one to three months. The analysis reveals volunteers’ motivations to be first and foremost altruistic; however, internationals are also influenced by other, more self-centered motivations, including their desire to learn through hands-on skills, and to advance their career. Motivations to prolong their volunteer commitment or to return to Greece particularly include social bonds built during previous engagements, the incentive to reduce feelings of guilt over being more fortunate than others, and the desire to relive experiences of increased self-fulfillment and personal growth. Dividing the sample by gender and age illustrates somewhat differing motivations among the sub-samples, leading to the conclusion that volunteers’ motivations are diverse, multifaceted, fluid, and placed somewhere along a spectrum between altruistic and egoistic aspirations. The study of people’s experiences overall suggests high satisfactions among the volunteers; however, sentiments of feeling at times overwhelmed and stressed are very present among most volunteers, regardless the length of their stay Greece or their performed activities. The workload, a too heavy burden of responsibility, lack of sufficient time to reenergize, lack of managerial support, and conflicts among volunteers particularly have the potential to lead to emotional exhaustion, depersonalized behavior, and challenges when returning home.