Technical Abstract: Four Verticillium dahliae isolates were used in screening four cotton cultivars. Pima S-7 and Acala Prema gave the highest resistance reactions and Acala 44 was the most susceptible. Isolate V76 of V. dahliae was the most virulent. An interspecific cross between the resistant cv. Pima S-7 and the susceptible cv. Acala 44 was made and the F2 population phenotyped for Verticillium wilt effect. Phenotyping of plant reaction to the disease was quantified by using a set of six growth parameters measured 3 weeks after inoculation. The F2 phenotypic distribution of these parameters suggests that distribution is towards resistance and polygenic. Transgressive segregation also was observed. The number of healthy leaves and total shoot weight were found to be the best indicators of resistance. Results obtained in this study will be useful to quanitify resistance to V. dahliae and identify the best parameters to phenotpye in genetic studies.