We evaluated cold-tolerance responses of 144 plant introductions (PI) of maize (Zea nqys L.), attempting to include in our sample at least one PI adapted to each of the countries or ecological zones represented in the maize germplasm collection at the NorthCentral Regional Plant Introduction Station at Ames, Iowa, USA. Plant introductions were grown for 42 days in plastic boxes (26 cm long x 19 cm wide x 10 cm deep) in a growth chamber maintained at 10 & 1 "C. Cold-tolerance responses of each PI were evaluted by three traits: 1) percentage emergence (recorded 30 days after planting), 2) emergence index, an estimate of rate of emergence, and 3) seedling dry weight (sampled 42 days after planting). Estimates of variances and heritabilities for these three traits were large, suggesting that genotypic variation for cold tolerance in the maize germplasm collection would be sufficient to permit selection advance. Furthermore, genotypic correlations among the three traits were high: therefore, improvement by index selection should be possible. Correlations between the cold-tolerance traits and days from planting to 50% silk emergence (an estimate ofmaturity obtained at Ames. Iowa, USA) were low. Days from planting to 50% silking emergence for the 25 most coldtolerant PI's ranged from 46 for PI 214279 from Canada to 106 for PI 331440 from Ethiopia. It should be possible, therefore, to develop cold-tolerant genotypes adapted to al1 latitudes.