Going beyond a technocratic e-government paradigm, this research aims at analyzing how, through the two-ways interaction supported by Web 2.0 technology, skilled external collaboration and knowledge-sharing between citizens and public administrations can offer new ways of citizen participation, enhancing political decision-making process and public value creation. Particularly, the purpose is to investigate how skilled citizens can serve as contributors to tasks that are traditionally performed by designated civil servants and now are outsourced to an undefined, generally large group of people, in the form of an open call for contributions. To this end, we have conducted a field research in order to identify and evaluate what is currently taking place in the Municipality of Palermo in the framework of citizen sourcing which may be realized by enhancing sharing knowledge and information flows through citizen engagement in order to reach a sustainable service improvement and therefore build or restore trust in local government. In the framework of Performance Management, the System Dynamics perspective will be followed with the aim of supporting municipal management to keep under control key-variables driving performance in the ongoing open innovation process