In an effort to cut costs and re-focus on their core competences, an increasing number of German companies are outsourcing software projects to low-wage countries like India or Russia. However, first experiences of these companies with offshore software development have not been consistently positive. Martin Wiener examines the critical success factors of such projects. The author develops a model that comprises 29 critical success factors which are classified into four distinct groups: internal suitability, internal management, external suitability, and external management factors. With regard to the developed model, both the implementation of an online survey and the conduction of two in-depth case studies show that the external management factors are particularly relevant for the successful implementation of an offshore software development project and that the perception of the individual critical success factors greatly depends on the company perspective.