ABSTRACTResearch Question/IssueThis paper investigates the antecedents of lead director selection in the US context. Specifically, how do rational and social factors influence the likelihood of being selected as the lead director?Research Findings/InsightsResults for independent directors in S&P 1500 firms from 2000 to 2021 support the positive effect of both board capital (human capital and social capital) and social embeddedness with the CEO (university ties and demographic similarity) as factors in the selection of lead directors. Results also show that among late adopters, the effect of human capital (board experience) on selection is strengthened, and the effect of demographic similarity to the CEO on selection is weakened.Theoretical/Academic ImplicationsFirst, building on the director selection model, this paper further differentiates the rational and socialized perspectives by integrating the diffusion model. Specifically, among late adopters, rational factors play a larger role, and socialized factors play a smaller role in the lead director selection. Second, for the literature on the boards of directors, this paper provides unique individual‐level insights about directors' attributes and their interactions with firm‐level timing of practice adoption.Practitioner/Policy ImplicationsThe new governance practice of having a lead director, a leader of independent directors, has emerged and spread in the United States since 2000. As attention to the lead director governance practice increases, this paper focuses on the complexity of its adoption. Specifically, both rational (board capital) and socialized (social embeddedness with the CEO) factors can play a role in the lead director selection. Related stakeholder groups such as directors, investors, and policymakers should be aware of the potential symbolic adoption of this new governance practice.