The use of Open Educational Resources (OER) for training in public administration has yet to see a wide adoption globally, mostly due to challenges related to the discovery and reuse of high-quality OER for training purposes. These challenges, combined with the general lack of openness in the public sector, have greatly impacted the penetration of OER in public administration. This paper presents a case study on the use of OER for expanding and enhancing curricular and resource sharing in public administration in Greece. Within this case study, an OER authoring and sharing platform was introduced to the Greek public sector, employing crowdsourcing methods for supporting trainers and trainees in authoring, sharing, reusing and remixing OER. The paper presents the deployment of this platform and the use of OER in the context of training programmes in the Greek public sector and reports on the lessons learned and the impact on public administration. The results of the case study showed that the use of OER was very positively received by civil servants, with a remarkable response, through active participation and engagement that led to the enhancement of existing OER and the co-creation of new ones for public administration.