This delivery process defines a significant number of "roles." Tasks in the process specify the roles that are involved in their execution. Roles are a purely logical view of performers on the project team. At a given point in time, a given person may be acting in any role or combination of roles, and the roles assumed by a given person will typically vary over time, dependent on both the current state of the project and the skills of the person.

The assignment of individual team members to specific roles, an assignment that may change over time as the project proceeds, is a project management responsibility, and is reflected in the project's plan. The itemization of a large number of roles in this process documentation does not mean that you will necessarily have a large project team. Again, the typical project scenario is that one individual will assume multiple roles.

The definition of roles allows for projects with any level of staffing. Large projects might assign specialists to individual roles, while smaller projects will tend to assign multiple roles to a single person. Roles in this process are defined based primarily on required skill sets and specialized knowledge, and are also sometimes differentiated based on the current project status (such as "phase").