Abstract:The paper focuses on the importance of an early engagement of stakeholders to manage the project along its entire life cycle. An increasing level of uncertainty and complexity tends to generate an increasing level of unpredictability, since it is difficult to anticipate all the possible dynamics, internal and external, affecting a complex project. Improving the forecasting/ planning process requires the usage of all the data available to the project team, in particular when facing a high level of uncertainty and complexity. In fact, stakeholders are the main sources of knowledge about the project and their early engagement may significantly increase the amount of knowledge, both explicit and tacit, available. As a consequence, project planning and control may be considered as a participatory process resulting from the interaction of the project team with all the stakeholders involved in the project.Keywords: data management; project planning and control; project uncertainty and complexity; forecasting process; knowledge sources; early engagement of project stakeholders.Reference to this paper should be made as follows: Caron, F. (xxxx) 'Data management in project planning and control', Int.