Abstract : As a result of continuing concern with large cost overruns in a broad range of major defense programs, Congress enacted new statutory provisions extending the ambit of the existing Nunn-McCurdy Act. In accordance with the revised Nunn-McCurdy law, the Performance Assessments and Root Cause Analysis (PARCA) office must provide its root cause explanation as part of a 60-day program review triggered when the breach is reported by the applicable military department secretary. This report does two things. First, it analyzes the root cause of cost overruns in two programs: the Army Excalibur artillery round and the Navy Enterprise Resource Planning (ERP). The Excalibur project incurred a Nunn-McCurdy breach. The ERP did not, but the cost growth was so great that the Department of Defense (DoD) requested a root cause analysis. Second, it presents what can be described as an exercise to help identify the most critical features of a program. Critical program components are those that carry the most risk of overall program failure. The exercise is designed to identify the important program features that decisionmakers would want to concentrate on when inquiring about a program as it develops over time. The report then uses the results of the exercise to flag the most critical features of the weapon system, using Excalibur as an example. The exercise and the illustration help to frame one approach for considering program failure risk in programs that have not yet breached.