For almost thirty years, the Nunn-McCurdy Act has served as one of the principal mechanisms for notifying Congress of cost overruns in Major Defense Acquisition Programs (MSAPs). Nunn-McCurdy establishes different thresholds to determine if an MDAP or designated major subprogram of an MDAP experiences a cost overrun. These thresholds are based on a comparison between a program's actual costs and the current baseline estimate or the original baseline estimate. A program that has cost growth that exceeds any of these thresholds is said to have a Nunn-McCurdy breach and must notify Congress of the breach. This book analyses the background and issues for Congress of the Nunn-McCurdy Act and defence spending overruns.