This text is intended for researchers in health services, medicines use andprofessional practice who are undertaking a multi-centre researchproject involving data collection in, or relating to, more than onecountry. Research across international boundaries presents its ownchallenges in that attention has to be paid to the relevance of researchobjectives, and feasibility of procedures in different settings whilemaintaining a scientific approach in terms of design, instruments andexecution.