In 1995, The U.S. Postal Service approached the Lawrence Berkeley National Laboratory for assistance in improving the energy efficiency of their facilities and in preparing to address the challenges and opportunities of the then-looming electricity restructuring. Over the last 8 years, LBNL has assisted the USPS with a wide variety of energy-related issues, including buying electricity and green power in competitive retail markets, collecting and analyzing energy consumption data and setting consumption reduction goals, re-designing lighting for mail sorting, designing on-site renewable projects, improving the Postal version of an energy savings performance contract and designing an overall energy management program for the USPS Pacific Area (California, Hawaii, Nevada and Arizona). During the course of our work together, among other achievements, the USPS has made the then-largest federal purchase of green power, installed the then-largest federal civilian agency PV system and completed tens of millions of dollars of energy efficiency retrofits. The USPS energy program has received numerous awards for work that was assisted by LBNL, recently culminating in the receipt of the Presidential Award for Leadership in Federal Energy Management last October. This talk will describe both the technical and organizational challenges faced in designing and implementing this award-winning program.