Broadening the genetic base is essential for continuous genetic improvement of cotton's (Gossypium hirsutum L.) yield, fiber quality, and pest resistance. A germplasm population was developed by crossing twelve cultivars and strains of G. hirsutum with four wild tetraploid species in the genus. This population, designated as the Species Polycross (SP), was initiated in North Carolina by P.A. Miller in 1967. It underwent 10 years of mixed intercross by natural pollination in an isolated area in North Carolina and 12 years of predominant selfing at Stoneville, Mississippi. The objectives of this experiment were to evaluate the SP population for genotypic variations in yield and fiber quality, and group genotypes for yield and fiber quality by cluster analysis. Two hundred and sixty SP lines were evaluated at two locations with two replicates each in 2005. Five cultivars, used as standards in the National Cotton Variety Trail, were also included in the evaluation. A tremendous amount of genotypic variation was identified for yield and fiber properties. The five cultivars had averages of 315 g/plot, 218 kN m kg-1, 13.7 mm, and 5.49% for yield, fiber strength, span length (50%), and short fiber content, respectively. The SP lines grouped into nine sequential clusters based on yield parameters and fiber properties. One cluster (Cluster 2) of 27 SP lines had cluster means of 238 g/plot, 241 kN m kg-1, 14.3 mm, and 5.12% for yield, fiber strength, span length (50%), and short fiber content, respectively. Another cluster (Cluster 6) of 11 SP lines had cluster means of 341 g/plot, 226 kN m kg-1, 14.8 mm, and 5.19% for the same respective traits. The cluster means of fiber quality in the other clusters were lower than the standard cultivars. The SP lines in Cluster 2 and Cluster 6 are elite for performance in either fiber quality or both yield and fiber quality compared to the standard cultivars. The results indicate that SP population is a useful germplasm resource. It also provided evidence that cluster analysis is a powerful tool for classification of cotton germplasm for yield and fiber quality.