Pea (Pisum sativum L.) is an important crop from an agronomic and nutritional standpoint. Winter pea has further agronomic benefits for producers; however, sufficient winter hardiness to survive harsh North Dakota conditions is lacking. Winter hardiness was evaluated in the field and greenhouse using replicated trials with 267 recombinant inbred lines derived from the cross ‘Medora’/‘Melrose’. Similar reactions were observed between the two trials. An optimum protocol based on acclimation time and scoring method to predict winter hardy genotypes using controlled environment conditions was studied. Twelve genotypes were acclimated for 0, 1, 2, 3, and 4 weeks at 4 degrees Celsius prior to being frozen at -8 or -12 degrees Celsius for 1 hour. Three weeks of acclimation and scoring 21 days after freezing provided the best differentiation among genotypes. This research provided direction for development of winter pea varieties suited to the harsh winter conditions of North Dakota.