This paper describes the introduction of a novel system to steer and control projects in small and medium sized enterprises in the German trade sector. These businesses are facing increasing competition and need to find innovative ways to organise processes more professionally. Trade businesses usually plan projects accurately, but once a project has started, the plan does not necessarily reflect the changes that occur in real life. Reporting is usually done on paper with insufficient processing time and therefore problems can not be taken care of in an adequate fashion. The introduction of PDAs to those businesses as mobile devices for steering and controlling proves to make these processes more efficient. Therefore we explore relevant business processes in the building trade, the singular properties of PDAs and related software developing issues as well as introducing our project steering and controlling system.