Successful project development is characterized by a multitude of risks and high uncertainties. Particularly for the correct assessment of the input data, such as market and location factors, as well as the right estimation of the requirements of the user, high competences are demanded by the project developer. Many decisions, which are required for a successful project development, therefore have to be made in very early stages of the development process. Based on this it has been postulated that an early involvement of stakeholders in the process of project development has influence on the project success. In this context there was executed a quantitative survey to examine competences of planners, contractors, brokers and operators to influence deducted success factors of project development. Findings revealed that the early integration of the participants influence the project success strongly. Particularly planners have a very high influence on object based factors like building design and layout of the ground plan. For optimizing the market and location factors also an integration of brokers and operators is essential. For developers it is recommended that they are informed of the possibilities of influencing the different success factors by an integration of the main participants. So the security for project relevant decisions in the early stage of the development process can be provided.