- Responsible: Those who do the work to achieve the task. There is typically one role with a participation type of Responsible, although others can be delegated to assist in the work required.
- Accountable (also Approver or final Approving authority): The one ultimately accountable for the correct and thorough completion of the deliverable or task, and the one to whom Responsible is accountable. In other words, an Accountable must sign off (Approve) on work that Responsible provides. There must be only one Accountable specified for each task or deliverable
- Consulted: Those whose opinions are sought; and with whom there is two-way communication.
- Informed: Those who are kept up-to-date on progress, often only on completion of the task or deliverable; and with whom there is just one-way communication.
The PMBOK Guide 4th Edition (starting in section 9.1) defines RACI as a responsibility assignment matrix (RAM) which is used to illustrate the connections between work packagers or activities and project team members. On larger projects, RAMs can be developed at various levels. For example, a high-level RAM can define what a project team group of unit is responsible for within each component of the WBS, lower level RAMs are used within the group to designate roles, responsibilities and levels of authority for specific activities. The matrix format shows all activities associated with one person and all people associated with one activity. This also ensures that there is only one person accountable for any one task to avoid confusion. The
PMBOK confirms that one example of a RAM is the RACI chart, showing the work to be done in the left column as activities. The assigned resources can be shown as individual or groups. The RACI is just one tye of RAM; the project manager can select other options such as "lead" and "resource" designation or others as appropriate for the project. The RACI is particularly important when the team consists of internal and external resources to ensure clear divisions of roles and expectations.