From region to region and even within states, the energy-efficiency program industry uses different terminology. Definitions of such key terms as lifecycle savings, net savings, and incentives vary depending on the jurisdiction. This diversity in semantics is a natural product of the different values and approaches that each state’s policymakers have adopted for energy efficiency but makes “apples-to-apples” aggregation of program inputs and outputs difficult and less meaningful. Inconsistency in efficiency program data poses a barrier to quantifying the energy efficiency resource on a regional and national basis and therefore undermines the notion that this resource is a material contributor to energy needs. Lawrence Berkeley National Laboratory (LBNL) has assembled a national taxonomy of energy efficiency (EE) programs and a common terminology for data on energy savings, program spending and other metrics for characterizing customer-funded efficiency programs. This common lexicon was founded on the work of the EM&V Working Group of the State and Local Energy-Efficiency Action Network (SEE Action), augmented with extensive reviews of programs in a majority of states by LBNL, the Consortium for Energy Efficiency and other national and regional organizations. CEE worked with LBNL to adapt this taxonomy for its State of the Efficiency Program Industry survey, fielded annually to efficiency program administrators across the US and Canada. LBNL and CEE will describe the practical usefulness of the program taxonomy and data glossary in analyses of the energy efficiency industry. LBNL staff will discuss the value of its adoption by a variety of energy sector stakeholders.