Cylinder deactivation was evaluated both analytically and experimentally on a six cylinder diesel engine to understand potential fuel economy and emission improvements. The benefits of cylinder deactivation in Spark Ignited (SI) engines are well documented, however there is little information on the application of the technology for diesel engines.The analytical model was evaluated at low load, steady state conditions. The modified baseline model that includes cylinder deactivation maintains comparable emission levels through the optimization of Exhaust Gas Recirculation (EGR) and Variable Geometry Turbocharger (VGT). The results demonstrated reductions in Brake Specific Fuel Consumption (BSFC) and higher exhaust gas temperatures for low and part load operating points. An experimental test validated the analytical results. Disabling fuel injectors and the valve train on half of the engine's cylinders allowed for the implementation of cylinder deactivation. Lower engine pumping work and reduced heat transfer to the cylinder walls resulted in reduced fuel consumption. Lower air flow rates, higher firing cylinder temperature, and lower total engine heat rejection contributed to increased exhaust temperatures. The analysis includes a tradeoff between exhaust enthalpy and exhaust gas temperature.Steady state BSFC improvements were demonstrated in the range of 10% to 30% for the speed load points studied without compromise to engine emissions. The GT Power  model analytically demonstrated sufficient benefit to justify an engine experimental evaluation. Experimental results are comparable to analytical results. The benefits are similar to current production gasoline engines employing cylinder deactivation. Experimental and analytical results provide sufficient data to assist in establishing the potential benefits of cylinder deactivation for select diesel applications.