This document summarizes the AC Transit Fuel Cell Bus Longevity Study report, which details how the Center for Transportation and the Environment (CTE) led a team from AC Transit in the extended monitoring of 13 Fuel Cell Electric Buses (FCEBs) as a part of the Federal Transit Administration’s (FTA) National Fuel Cell Bus Program (NFCBP), working with AC Transit, UTC Power, EnerDel, Van Hool, Siemens Industries, and Dynetek Industries in this endeavor.