In the 1920s and 1930s, the Sentinels of the Republic, a conservative citizens' organization, mounted a fierce campaign against the adoption of the federal Child Labor Amendment. The Sentinels were able to defeat the amendment by painting it as a threat to the sovereignty of the male-headed family. This appeal proved an effective rallying cry across sex, class, and faith lines, and galvanized significant opposition to the expansion of state power. Initially formed in 1922, the Sentinels, composed predominantly of elite businessmen, lawyers, and antifeminists, remained an active antistatist lobby throughout the following two decades, and formed a key part of the pro-business lobby that attacked the New Deal. Assessing the gendered political ideology and organizing strategies of the Sentinels reveals how patriarchal ideas about the traditional family played a core and constitutive role in the development of conservative free-market politics.