sentences: As CMOS technologies have shrunk to tens of nanometers, aging problems have emerged as a major challenge. There has been tremendous progress in developing new methods for modeling and diagnosing reliability at the level of individual transistors, but much less work on propagating these models to higher levels of abstraction to analyze and optimize the reliability of larger circuits. This talk will provide an introduction to various circuit aging mechanisms and will then discuss research that develops computer-aided design techniques for estimating and enhancing the reliability of large digital circuits, examining solutions that could practically be applied to analyze or improve the lifetime of a design while maintaining consistency to accurate device-level models and the associated physics.