The roles of major gene and multifactorial inheritance in the etiology of clubfoot (talipes equinovarus) were studied using Caucasian clubfoot families ascertained in Indiana. The method of analysis used was complex segregation analysis under the mixed model, in which five genetic parameters were examined to test hypotheses on major gene by displacement (t), degree of dominance (d), gene frequency (q), transmission probability (tau2), and multifactorial inheritance by heritability (H). The analysis showed that the segregation pattern of clubfoot in these families is best explained by assuming the action of a major gene with additional contribution of multifactorial inheritance. The estimates of the parameters under the best-fitting model were d = .82, t = 4.69, q = .030, tau2 = .50, and H = .17.