The aim of this thesis is to develop a comprehensive assessment for Corporate Social Re-sponsibility (CSR) which is here defined as social sustainability. The CSR-assessment is aimed to enable firms from the energy and materials industries to actively integrate stakeholders in the assessment process. The methodological procedure of the thesis and the assessment is based on the cognition theory as well as on systems theory. For the determination of CSR-aspects, industrial firms are discussed from a CSR perspective. Therefore, claims of stakeholders as well as of the company towards CSR are deductively derived and finally validated empirically by sustainability experts. Finally, a reference model with 20 CSR-aspects is defined. These aspects describe the CSR commitment of a firm in a generic manner. Guidance is pro-vided for companies to demonstrate how to handle these CSR-aspects. In order to develop a substantiated assessment, already existing assessments are evaluated, based on three criteria groups (completeness, practicability, quality of reproduction). The analysed models show various strengths and weaknesses; distinct ideas can be further used for the de-velopment of an appropriate assessment. Based on the defined CSR-aspects, a CSR-assessment is developed in order to provide companies with useful systematics, to control the actual situation and to develop specific measures in order to reach defined goals. The CSR-assessment consists of six steps and is designed to be used as a kind of controlling method, with the embodiment of several ma-turity levels. Different to existing self-assessments, the here proposed model actively integrates relevant stakeholders into the assessment and therefore allows for a balanced perspective on CSR. The assessment enables the firm to learn effectively regarding CSR, the conduction of change processes with the already defined CSR goals so that improvement towards CSR is assured. Finally, the CSR-assessment is conducted in a European steel company and hence to validate the practicability of the CSR-assessment.