Purpose - To identify and discuss the changes arising within very large law firms from the pressure to provide global services and the issues for firms in implementing cross-border integration. Design/methodology/approach - The research is qualitative, case-based and exploratory, using a piloted topic guide. The study is of very large UK "City" law firms (i.e. those operating in over 20 countries) using in-depth semi-structured interviews with: managing partners, senior partners, partners and associates at "City" law firms, clients, US lawyers in London and non-legal professionals. Data are triangulated with information from trade press, trade associations and firm reports. Findings - Identification of managerial issues of global integration common to law firms inter-viewed. These include: a shift to a "managed" firm and decline in professional autonomy; post-acquisition integration and merger process issues; operationalization of global practices (such as common technology platforms, common systems practices, common human resources management practices and cross-border intra-firm working relationships) to achieve consistency throughout the integrated firm. Research limitations/implications - Data set is derived from UK firms only and dependent on respondent views. Findings indicate that law firms have become less distinctive and more like other service businesses. Practical implications - The paper identifies the processes by which consistent cross-border service to the client may be achieved within globally integrated firms. Originality/value - Law is an under-researched industry. This research adds to knowledge of the legal services industry; explores globalization in a professional service firm context; extends the global strategy literature into the services domain. This is also one of the few papers on law firms based on primary data.