On the way to process automation, an important issue is the definition of the various activities or work tasks within the respective business process. Design decisions on this issue considerably affect business performance. Several guidelines known in the area of workflow management exist, but do not give the inexperienced workflow designer much to hold on to. This chapter introduces a cohesion metric that can be used for the identification of weakly cohesive activities in a workflow design. Also, a heuristic is presented that is based on this cohesion metric to decide between various workflow design alternatives. A theoretical and an empirical evaluation are included in this chapter, both positively supporting the soundness of the metric. The inspiration for the introduced notion is derived from similar cohesion metrics in software engineering.