Two winter pea lines [Pisum sativum subsp, arvense (L.) Poir], ‘Fenn’ and ID 113, and one spring pea cultlvar (Pisum sativum L. ‘Dark Skin Perfection’) (DSP) were acclimated for 1 to 7 weeks, and frozen to determine the rate and extent of acclimation. Dry weight and percent moisture were measured after each week of acclimation on leaf, stem, and root tissues. Freezing tolerance of the two winter pea lines increased during the first 4 weeks of acclimation, attaining a minimum mean lethal temperature of −8.5 C. Survival of the spring pea cultivar, DSP, did not improve with increasing exposure to acclimating temperature. All DSP seedlings were killed with freezing stresses of −9 and −12 C, and survival averaged less than 5% at −6 C. Dry weight accumulation during acclimation did not vary among genotypes and proceeded at linear rates of 1.95, 0.9 and 1.7 mg plant−1 week−1, in leaves, stems and roots, respectively. Percent moisture declined in all tissues of winter pea seedlings, while remaining constant in DSP seedlings. Neither rate of accumulation nor distribution of dry matter were related to freezing tolerance. Percent moisture and freezing tolerance were inversely related during acclimation. However, percent moisture of winter pea seedlings continued to decline after acclimation was completed.