When tasks are defined and schedules are estimated, the planning effort has sufficient information to begin staffing plans and organizing a team into units to address the development problem. The comprehensive staffing plan identifies the required skills and schedules the right people to be brought onto the project at appropriate times and released from the project when their tasks are complete.
Selection of individuals to fill position in the staffing plan is a very important step. Errors in staffing can lead to cost increases and schedule slips just as readily as errors in requirements, design, or coding.