Through a historical case study of the internationalization of large English law firms in Italy, this paper uses Scott’s three pillars approach (2005) to look at how local institutions constrain and mediate the strategies and practices of professional services firms (PSFs). In doing so, it corrects the economic bias in the growing body of literature on the internationalization of PSFs by stressing how local regulations, norms and cultural frameworks affect the reproduction of home country practices, such as the one firm model pursued by large English law firms, in host-country jurisdictions. The paper also extends existing work on institutional duality (Kostova, 1999, Kostova and Roth, 2002) by developing a fine grained, micro level analysis which emphasizes the connections between institutions and practices. This is crucial, we contend, since the difficulties encountered by PSFs (and multinationals more generally) in their internationalization do not result from collisions between home- and host-country institutional structures per se, but between the diverse practices generated by distant institutional environments.