This study examines the formation of linking norms among political bloggers and professional journalists. Through in-depth interviews with Web editors, reporters, and bloggers within and outside professional newsrooms, it explores the institutional and cultural forces at work in determining whom blogs and news sites link to, and in what contexts. Drawing on the framework of institutionalism, this study aims to supplement research on journalistic normalization and hyperlink patterns by providing a fuller understanding of the processes by which professional journalism and the political blogosphere mutually adapt toward new norms. It finds a significant role for blogging's cultural values in establishing the importance of linking within professional newsrooms, but also a heavy influence on journalists' linking practices from bureaucratic processes within those newsrooms.