A description is given of a procedure for certifying the reliability of software before its release to users. The ingredients of this procedure are a life cycle of executable product increments, representative statistical testing, and a standard estimate of the MTTF (mean time to failure) of the product at the time of its release. The authors also discuss the development of certified software products and the derivation of a statistical model used for reliability projection. Available software test data are used to demonstrate the application of the model in certification process.