The yield stress of asphalt emulsions was investigated as a potential quality control parameter. Viscometric data were determined using concentric cylinder, parallel plate, and cone and plate geometries. The use of a novel slotted-plate technique was investigated to determine the yield stress of asphalt emulsions in a direct way, that is to say, without extrapolation. The Saybolt viscosity was determined following the AASHTO T 72-97 standard procedure. It was found that the slotted-plate technique produced reproducible and consistent results, which were far superior to those obtained by rotational rheometer techniques. The yield stress of the emulsions appears to be a more accurate measure of the performance specification for asphalt emulsions than the Saybolt data.