This thesis deals with the integration of two apparently conflicting manufacturing improvement concepts; Lean Production (LP) and Enterprise Resource Planning (ERP). On the one hand, Lean Production aims at process excellence with a decisive focus on people, emphasizing standardization, material flow, quality and continuous improvement. On the other hand, Enterprise Resource Planning, largely focuses on Information Technology (IT) in order to improve processes and operations. Referring to these basic underlying paradigms, it appears that there are fundamental differences between these two concepts. Based on a literature review in the field of operations and IS, the thesis identifies major differences, compares strengths and weaknesses and looks for theoretical synergies between the two concepts. In the light of the literature review findings, the thesis suggests a theoretical framework for integrating Lean Production and ERP, which is to be tested during the empirical part of the thesis. The theoretical framework is informed by two basic and partly contradictory assumptions, which could be viewed as contradictory research hypotheses. The first assumption holds that due to the fundamental differences, conflicts between the concepts will prevent the application of an integrated framework combining ERP and LP. The second assumption presumes that there were synergies between ERP and LP, which could be utilizable within the application of an integrated framework combining ERP and LP. Based on a detailed a case study, this research shows that the application of an integrated approach was possible in practice. In particular, the research identifies practical conflicts and shows how they could be overcome. In this respect, the involvement of the company's top management turned out as a major success factor for overcoming general preoccupations of each side's proponents against the other. Moreover, the research identifies practical synergies between the concepts and identifies how they could be utilized in practice. In this context, the case study suggests that, amongst others, the concept of LP benefits from ERP's enterprise wide reach and the concept of ERP benefits from LP's ability to attract top management attention. Moreover, there are several conceptual synergies, which could be revealed after removal of the general preoccupations. Eventually the findings are summarized in a new release of the integration framework between LP and ERP, informed by the empirical findings of this research.