Open Culture Data started as a grassroots movement at the end of 2011, with the aim to open up data in the cultural sector and stimulate (creative) reuse. In this context, we organised a hackathon, which resulted in the creation of 13 Open Culture Data apps. After this successful first half year, a solid network of cultural heritage professionals, copyright and open data experts and developers was formed. In April 2012, an Open Culture Data masterclass started in which 17 institutions got practical, technical and legal advice on how to open their data for re-use. Furthermore, we organised an app competition and three hackathons, in which developers were stimulated to re-use Open Cultural Datasets in new and innovative ways. These activities resulted in 27 more apps and 34 open datasets. In this paper we share lessons-learned that will inform heritage institutions with real-life quantitative and qualitative experiences, best practices and guidelines from their peers for opening up data and the ways in which this data is reused. Since the open culture data field is still relatively young, this is highly relevant information needed to stimulate others to join the open data movement. To this end, we are already taking steps to cross the borders and let Europe know about the initiative, on both a practical and a policy level.