Techniques are described for managing interactions between workflows being performed by different applications, such as to enable a combination of multiple workflows in multiple applications of different types to aggregate varying capabilities available from the different types of applications. In some situations, an integrated workflow is created by separating portions of its functionality into multiple constituent workflows that is each performed by a different application and that initiate one or more inter-workflow interactions between the constituent workflows as they are performed (e.g., for one of the constituent workflows to, while it is being performed, invoke another constituent workflow in order to begin its performance). As one non-limiting example, the multiple applications of different types may include a least an enterprise business application program that provides various core business functions, and a desktop collaborative application program that provides various user activity management capabilities.