Corporate Social Responsibility (CSR) of corporations is a trend today. However, the more companies are practicing it, the less it becomes a unique business strategy helping to differentiate from competitors. For that reason, this study examines whether an integration of customers in all decisions and/or the carrying out of different CSR activities leads to it being a more effective marketing strategy. In the conceptual part, a definition of CSR is given: Different approaches are presented reaching from a more detailed one dealing with economic, legal, ethical and discretionary responsibilities according to the pyramid of CSR, to a less specific one, which is taken as the basis of the paper. Key characteristics of CSR as well as different motivations exemplified in the normative and the business case are described and a critical evaluation of CSR is taken into consideration by means of the shareholder view of CSR and the stakeholder theory. Moreover, CSR in Germany is compared with CSR in America in order to give a global perspective of the CSR phenomenon. Furthermore, the most common CSR activities are introduced. From those, cause-related marketing, employee volunteering, and corporate philanthropy are detailed with real company examples and respective advantages and disadvantages because those are the activities used in the study. A review of appropriate literature is given and for customer-related outcomes, social identity theory, attribution theory, and behavioral decision theory are regarded. The concept of customer integration has been adopted from the product innovation process, called open innovation, to CSR by using the means-end theory and the empowerment strategy. Taken together, the hypotheses have been development stating that customer integration leads to a more positive CSR belief, a stronger identification with the respective company as well as a more positive company evaluation and a much higher intent to buy the corporation's product. These hypo