A national data infrastructure (NDI) provides data, data-related services and guidelines for the re-use of data as an easily accessible service to citizens as well as public and private organizations. As such, it allows the efficient sharing of data between providers and consumers, supports new business models, and is thus a key enabler for the digital economy, societal collaboration and political processes. The paper relates to an ongoing project, discusses prevailing concepts on (data) infrastructure development and proposes a classification scheme for conceptualizing national data infrastructures in a given context. The discussion in particular focuses on governance issues related to establishing and maintaining a national data infrastructure that goes beyond the focus on open government data.