Pearl millet [Pennisetum glaucum (L) R. Br.] is an important cereal crop in Niger and a potential crop for the United States. Only a few studies have been conducted in both countries to identify the optimum planting dates for high and stable yields, in part because planting date experiments are resource intensive. However, crop simulation models can be a useful tool for determining optimum planting dates and other management practices. After a model has shown to be able to simulate growth and development for a specific site, long term analyses can be conducted with a relatively good accuracy. The objectives of the present study were to evaluate the performance of the Cropping System Model (CSM)-CERES-Millet for two different environments, including Kollo, Niger (Africa) and Mead, Nebraska (USA) and to evaluate the effect of different planting dates on millet yield. Field experiments were conducted in both locations to study the impact of nitrogen fertilizer on grain yield of dwarf varieties and associated growth and development characteristics. The CSM-CERES-Millet model was calibrated using data from these two experimental sites and thereafter used for seasonal analysis. The model was able to accurately simulate growth, development and yield for millet grown in two contrasting environments, e.g., Kollo and Mead, and under different management practices that included several genotypes and nitrogen fertilizer treatments. For Kollo, the CSM-CERES-Millet model simulated high yields across 20 years of weather records for sowing dates from April 23rd to May 23rd. For Mead, the highest simulated yields using 35 year of historical weather data were obtained for the June 20 sowing date for all three hybrids. Millet planted later than July 9th showed a significant decrease in simulated yields. The CSM-CERES-Millet also assisted to identify the possible causes that explain the yield reductions in the different sowing dates.