About WBS Summary Activities
A WBS summary activity represents a group of activities that share a common work breakdown structure (WBS) level. The summary-level WBS activity enables the aggregation of dates and percent complete for the activity group. Aggregate values for a WBS summary activity are calculated when the project is scheduled. The duration of a WBS summary activity extends from the start of the earliest activity in a group to the finish of the latest activity.
You can assign resources to WBS summary activities and those assignments can be either driving or non-driving. If an assignment is driving, its dates are linked to the WBS summary activity and are adjusted to match the activity's dates. Depending on the duration type of the WBS summary activity, the assignments units or units per time are also recalculated. If an assignment is non-driving, its start date matches the start date of the WBS summary activity and the duration of the assignment will determine its finish date.
When you schedule the project, the dates and status of WBS summary activities are updated to match those of the activities it summarizes. Although you can assign relationships to WBS summary activities, they are not considered when the project is scheduled or leveled.
The WBS code of a WBS summary activity determines which activities comprise the group. For example, a WBS summary activity assigned to WBS code A, would aggregate values for all activities under any subordinate WBS that relates to code A: A.1, A.1.1, A.2, A.2.1, and so on. If the WBS summary activity in this case were assigned to WBS code A.1, it would aggregate values for activities under WBS A.1 and A.1.1, but not for those activities under A.2 or A.2.1.
Last Published Monday, October 13, 2025