Within the last six-eight years many papers have reported an association between increased levels of particulate (aerodynamic size less than 10 microns in diameter) air pollution and increased daily death rates and illness in major cities in the US, Europe, and South America. There is a need to better characterize the emission rates and chemical composition of particles emitted from vehicles equipped with the latest emission reduction technology. Particle-mass emission rates were measured for four 1995 Ford vehicles driven over three different driving cycles: the Urban Dynamometer Driving Schedule (UDDS), the Highway Fuel Economy Test (HFET), and the USO6 driving cycle. The average particle-mass emission rates were less than 10 mg/mi for any of the driving cycles. The particle-mass emission rate was least for the HFET and about equal for the UDDS and the USO6 cycles. The elemental composition of the particles, determined by X-ray fluorescence, suggests that 10-30% of the particle-mass is composed of metals, sulfur and silicon compounds.