Cool temperatures during the early growing season are a major limitation to growing sorghum (Sorghum bicolor (L.) Moench) in certain regions of the United States and other temperate areas. We have found that several sorghum landraces from China exhibit higher emergence and greater seedling vigor under cool conditions than typical American varieties. Unfortunately, Chinese sorghums also possess other undesirable traits. Directed introgression of seedling cold-tolerance genes from these landraces into elite, high-yielding lines, without the undesirable traits from the donor parents, could be expedited by marker-assisted selection (MAS). However, few studies have actually demonstrated the efficacy of MAS for major agronomic traits. The objectives of this study were to identify molecular markers associated with early-season performance through quantitative trait locus (QTL) analysis of a recombinant inbred (RI) population, and then to validate the significance of those QTL in a different breeding population. The parents of the RI mapping population were 'Shan Qui Red' (SQR), a cold-tolerant Chinese line, and SRN39, which is cold-sensitive. Composite interval mapping identified several QTL associated with percent emergence and seedling vigor in the field after early and more optimal plantings. Three flanking SSR markers, representing the three most significant QTL, were chosen for validation in two different breeding populations, developed by crossing SQR with Tx2794 or 'Wheatland', both of which are cold-sensitive. Individual F₃ families were genotyped for the markers, and early-season vigor and agronomic traits were measured in the field. Statistical analysis of the first year's data indicates that the influence of these QTL on early-season performance remained significant in both test populations, and that their associated markers should be useful tools for future selection efforts.