Peanut peg strength, which influences the proportion of peanut pods harvested, was measured as a function of the force required either to detach the peg from the pod or to break the peg. Pegs from 10 commercial cultivars and 30 plant introductions were tested for peg strength with an Instron Test Instrument. The mean peg detachment forces for Florunner, Florigiant, Spantex, Tamnut-74, and Toalson varieties were 10.0, 12.7, 13.0, 17.2, and 22.1 Newtons (N), respectively. Peg detachment forces for Plant Introductions 295210, 393523, 393530, and 393647 were 28.2, 35.2, 35.3, and 37.2 N, respectively. Peg anatomy and the intensity of phloroglucinol staining for lignin were directly correlated with peg detachment forces. Strong pegs had highly developed sclerenchymatous tissue and large crescentshaped, closely spaced, and highly lignified bundle caps. Bundle caps in weaker pegs were small, less compact, and spaced farther apart. Peg detachment forces and peg anatomy are criteria that could be considered in the development of improved peanut varieties.