The disclosure of open government data is a complex activity that may create public value yet might also encounter risks, such as the misinterpretation and misuse of data. While politicians support data release and assume that the positive value of open data will dominate, many governmental organizations are reluctant to open their data, as they are afraid of the dark side. The objective of this paper is to provide a decision-making model that assists in trade-offs between the pros and cons of open data. Data disclosure is dependent on the type of data (e.g. its sensitivity, structure and quality) and the context (e.g. organizational policies, legislation and the political influences). Based on the literature and fifteen in-depth interviews with public sector officials and data archivists, this paper identifies contextual and dataset-related variables which influence a trade-off. A decision-making model is presented capturing trade-offs, and in this way providing guidance for weighing the creation of public value and the risks. The model can be used for decision-making to open or not to open data. It is likely that the decision regarding which data should be opened or closed will shift over time.