This study utilizes a computer program that simulates selection, linkage, and environmental variation in finite populations. The intensity or magnitude of those factors is related to the genetic progress of small simulated populations under 9 genetic models, and the results are discussed in relation to existing theory. Populations with complete dominance, complementary factors, or duplicate factors were temporarily hindered in progress from selection by random drift, due to small population size, but the paucity of undesirable fixations indicates that the effect on total potential response should be negligible or small if selection is an intense as 1/6. Selection was effective in advancing the genetic mean of small populations under the models of gene action in which the genotype of highest merit is homozygous, but was weaker than random genetic drift when heterozygous genotypes were optimum. Little evidence was obtained to support Robertson''s hypothesis that less intense selection may be optimum for reaching long-time selection goals. Differences in the amounts of simulated environmental variation between populations were important in affecting genetic progress only when the mean was changing rapidly because of intense selection. Genetic merit, gene frequency, and fixation essentially were unaffected by different levels of linkage, except in the 1st few generations of some populations. Linkage disequilibrium appears to bias estimates of components of geno-typic variance for many generations in populations selected for intermediates.