Revision with unchanged content. Since more than 50 years development cooperation exists and has been analysed by scientists from different fields ever since. Supporters and critics find suitable arguments to strengthen their respective position. This book contributes to bring some light into the questionable impact and success of development cooperation. It is one of the few empirical studies accessible to the scientific community and to the general public. The two organisations UNOPS and GTZ are investigated in detail to address the question of their impact. Their contribution to development cooperation is analysed and recommendations are given. This book answers some central questions such as: What common grounds and differences do UNOPS and the GTZ - regarding their organisational structure, clients, and basic rules and regulations - have? How and with what success do the two organisations implement projects and programmes in the field in Peru and in Bolivia? An excellent overview on the two organisations is provided and lessons learnt for their future but also for the future development cooperation are pointed out.