Cone and seed maturity of Scots pine (Pinus sylvestris L.) were evaluated for three seed years and several plantations in prairie Canada. Both specific gravity and moisture content provided reliable measures of cone maturity and were directly related to viability of the seed produced. Individual trees were found to differ as to cone and seed maturity for successive harvests in three years. Cones were mature when specific gravity decreased to 1.02 or a moisture content to 38% and produced seed with a high germination capacity even after four years of storage (81 to 95%). Distilled water is recommended for field testing of cone maturity for individual trees. Number of seeds per cone and seed weight were more directly related to cone size than to cone maturity. Neither color of cones nor color of seeds proved reliable measures of maturity.