Increasingly stringent emission requirements for heavy-duty diesel engines stresses the importance of both engine design and diesel fuel quality. The Coordinating Research Council sponsored this test work to yield quantitative emission data and emission models to relate diesel fuel properties to emissions from modern heavy-duty diesel engines. Regulated and selected unregulated emissions from three engines were measured over the EPA transient test procedure using several fuels having controlled variation in three primary fuel properties: aromatics, volatility (as the 90 percent boiling point temperature), and sulfur.Models for transient composite emissions were obtained using multiple linear regression techniques, and changes to regulated emissions for selected changes in fuel properties were estimated from the models. Of the three primary fuel variables, aromatic content and volatility were significant for emissions of HC, CO, and NOx. Aromatics and sulfur were significant for total particulate. Decreasing fuel aromatic content, sulfur, and volatility (increasing 90 percent boiling point temperature) were generally associated with reductions to regulated emissions.