Agile development methodologies promise higher customer satisfaction, lower defect rates, faster development times and a solution to rapidly changing requirements. Plan-driven approaches promise predictability, stability, and high assurance. However, both approaches have shortcomings that, if left unaddressed, can lead to project failure. The challenge is to balance the two approaches to take advantage of their strengths and compensate for their weaknesses.

Barry Boehm and Richard Turner. "Observations on balancing discipline and agility." Agile Development Conference, 2003. ADC 2003. Proceedings of the. IEEE, 2003.