ONSTAGE is the data repository for Amsterdam’s first and most prominent public theatre venue: the Schouwburg. In theatre history, the Amsterdam Schouwburg has a fairly unique place due to its rich body of extant account books, programs and administrative records of annual play lists, and registers of expenses and revenues. These sources, as a most sensitive finger on the theatre’s pulse, can be used as analytical tools that provide access to the theatre’s artistic business, from its foundation in 1638 until today. This data paper is an assessment of the new ONSTAGE data system, in terms of its structure, the nature of the data and enrichment, and the research potential. The paper also explores future growth in linked data systems.