Successor is an activity that follows another activity according to the dependencies. The successor often is situated chronologically after its predecessor but also can lie before. Such situation should be prevented. The successor helps to manage many activities in the project management, which need planning and management. It defines which activity should follow and therefore provides the activity order in the planning. It is important to find out, which activity should be completed for organizational, technical or methodical reasons in order to define the predecessor. It should be considered, which activity can be started first for organizational, technical or methodical reasons in order to define the successor. In most cases it is enough to define only predecessors or successors. But the compilation of them both is better for a good controlling. The sequence between predecessor and successor should be in a logical order. It should take the logical plane in the time scheduling even, if it is hard to define whether an activity is a predecessor or successor.