Workflow Management Systems (WFMS) coordinate execution of logically related multiple tasks in an organization. A workflow schema is defined using a set of tasks that are coordinated using dependencies. Workflows instantiated from the same schema may differ with respect to the tasks executed. An important issue that must be addressed while designing a workflow is to decide what tasks are needed for the workflow to complete – we refer to this set as the completion set. Since different tasks are executed in different workflow instances, a workflow schema may be associated with multiple completion sets. Incorrect specification of completion sets may prohibit some workflow from completing. Manually generating these sets for large workflow schemas can be an error-prone and tedious process. Our goal is to automate this process. We investigate the factors that affect the completion of a workflow. Specifically, we study the impact of control-flow dependencies on completion sets and show how this knowledge can be used for automatically generating these sets. Finally, we provide an algorithm that can be used by application developers to generate the completion sets associated with a workflow schema.