This volume offers an in-depth description and discussion of research design for a large-scale investigation of bilingual development. It introduces and justifies a range of theoretical and methodological innovations, discusses some of the problems that come with these and proposes practical solutions. The present volume introduces a research design intended to capture a wide range of linguistic data, elicited by means of behavioral tasks, neuroimageing data and free speech from both second language learners and first language attriters of two languages (Dutch and German) representing a wide range of language combinations and ages of onset. Gathering and analyzing such a range of data comes with a multiplicity of problems, many of them linked to the fact that similar tests have to be designed across a range of languages and measurements will have to occur in various locations. The current volume presents a research design appropriate to these questions, discussing the methodological challenges of such a study. It offers advice on how to construct experimental materials which are parallel across different languages set up a protocol for additional measures which can be applied across a wide range of participants combine data from different labs when using different ERP equipment and different eyetrackers.