Technical Abstract: Few guidelines exist to enable soil scientists, soil conservationists, or landowners to take soil samples in a standardized fashion that will permit wet aggregate stability (WAS) or aggregate size distribution (ASD) to be adequately compared from site to site or from soil to soil. Since sample collection, handling, storage, and pretreatments affect these measurements, in this chapter we describe these effects and propose procedures that 1) do not significantly change aggregate properties from sampling to analysis, and 2) improve the precision and accuracy of measurements made on samples taken from a given field soil volume. Soil samples should be analyzed as soon as possible after they have been collected to minimize time in storage. If interested in WAS as present in the field, we recommend analyzing field-moist soil samples. These samples should be maintained field-moist and, if storage is necessary, stored in air-tight containers at 3 to 7 degrees C. The WAS of different treatments is probably best compared if, just before sieving, soil samples are 1) vapor wetted to a standardized water content or matric potential or (2) initially air-dried, depending on study objectives and soil properties. An investigator should focus on the aggregate size class(es) that best reveals the effects of the studied processes. In lieu of information to the contrary, we recommend 1 to 2 mm for air-dried aggregates or 1 to 4 mm for field-moist aggregates. Finally, we recommend that complete descriptions of soil sampling, handling, storage, and pretreatment (prewetting) be reported in any study of WAS or ASDs.