In 2006 Andrew McAfee introduced the term enterprise 2.0 and announced “the dawn of emergent collaboration” with its help. He uses this term in order to distinguish between social software and web 2.0 technologies in general and social software that is only used within companies . In fact McAfee was right, Enterprise social software industry is projected a compound growth rate of 42% between 2011 and 2016 and is believed to achieve US$6.4 billion  which shows the impact of enterprise 2.0. According to Richter and Riemer a key characteristic of social software is its open usage. They distinguish application software by the type of their usage which can be for a specific purpose or open, using several characteristics to describe them, i.e. their purpose (problem solving vs. creating potentials), usage (specific vs. diverse) and application (business process vs. open) . An emerging problem is the evaluation of enterprise 2.0 software due to their open usage characteristic. In open usage software several functionalities can be used to support a specific business process, similarly one functionality can be used to support multiple business processes thus making the evaluation of enterprise 2.0 tools difficult . Therefore a pattern based approach for evaluation is needed, laying focus on usage patterns instead of functionalities or business processes. The aperto 5-layer-model developed by Richter et al. bridges the gap between business processes and functionalities, hence offering a way to develop usage patterns based on collaborative use cases, which were collected in the context of the aperto framework. The goal of this thesis is to develop a pattern-based evaluation framework for enterprise 2.0 tools. In a second step the framework is used to evaluate the most common enterprise 2.0 tool(s) revealing advantages and limitations on one side of the tools but then again of the developed framework.