II: METHODS.

The methods described in this chapter cover the cohort data collection, which constituted the common data set for all three studies reported in this paper. A sample of 430 bilingual toddlers, learning British English and one of 13 target Additional Languages (N = 372), or any other Additional Language (N = 58), were identified over a 2-year period. To increase variation in both English/Additional Language pairs and in the situational factors outlined above (language exposure, mode of exposure and demographic factors), data was collected through trained research assistants recruited in the six universities involved in this project (Bangor, Birmingham, Kent, Liverpool, Oxford and Plymouth), as well as in Bristol and Leicester, each having access to multilingual populations to various degrees. However, since the testing platform was remotely accessible, the final sample comprised families from all areas of the UK, apart from Scotland and Northern Ireland. Bangor had the additional advantage of being located in a region with 75% bilingual Welsh-English children, providing a unique opportunity to compare language skills in bilinguals growing in a region with predominant bilingualism, to those whose bilingualism is linked to immigration.