Six sampling techniques were studied to determine the most efficient, practical, and accurate method for estimating populations of the spotted alfalfa aphid, Pterocallidium sp. These techniques included the inverse binomial count, leaf count, stem count, plant count, sweep net, and fork sampling. Based on the results of statistical analysis, the leaf count was selected as the best method. This consisted of counting the number of aphids on 3 trifoliate leaves, each selected at random from the top, middle, and bottom portions of the plants, respectively, and replicated 10 times at intervals of 20 to 50 walking steps in a diagonal fashion across the field.