This book provides a new procedure for decision making: SCEEN. This procedure is more effective than other procedures, since it treats all important steps and takes into account human mental capabilities and limitations. For instance, it is both structured and iterative. The term decision making as used here ranges from small decisions to very large decisions; from selecting the transport means for your trip from London to Paris to the design of a whole factory - including the processes for building, operating and maintaining it. The underlying decision-making processes for such different tasks are essentially identical. SCEEN was compiled from a number of existing procedures and newly performed case-studies. It may be regarded the 'mother' procedure for the other procedures. The book is primarily written for professionals and students in business administration and in system engineering.