Over recent decades, Greece’s civil society has undergone major changes, shaped by significant events and crises. Historically fragmented, with limited state recognition and negative public perception, the sector has recently experienced revitalisation and reform. This article explores how episodic volunteering during major events – specifically the Athens 2004 Olympic Games – can foster individual agency, develop skills and support sustainable practices within the third sector. Drawing on theories of social connectedness and sustainability, the study analyses the experiences of 19 professionals from national third-sector organisations. Findings suggest that episodic volunteering can contribute meaningfully to organisational capacity building and sectoral growth. However, limitations related to infrastructure and investment priorities may restrict its long-term impact. The article argues for strategic, sustainable approaches to harness the potential of episodic volunteerism while critically examining its constraints. Ultimately, it calls for more deliberate efforts to strengthen civil society infrastructure and promote sustainable development across Greece’s third sector.