The corpus of Sophie's bilingual development is the second installment of the Hong Kong Bilingual Child Language Corpus. Born on 28 February 1996, Sophie is the younger sister of Timmy, the first bilingual subject to be included in the Hong Kong bilingual corpus, born two years and nine months earlier (a younger sister was born when she was 4;03). Sophie's mother is a native speaker of Hong Kong Cantonese and her father of British English, and her exposure to Cantonese and English started from birth. The one parent-one language principle was adopted in principle, especially when addressing the child, but code-mixing occurred when the parents conversed with each other, which formed part of the child's input. Apart from parental input, interaction with her brother took place in both Cantonese and English. She was regularly video-taped and audio-taped by two research assistants in each recording session, one responsible for each language, from 28 August 1997 to 28 February 2000 (1;06 - 4;00) on a weekly basis. In each recording session one research assistant interacted with the child for approximately half an hour in English and the other for half an hour in Cantonese. The corpus as initially released covers transcriptions from age 1;06 up to age 3;00.09, on an approximately biweekly basis.

Sophie lived in Hong Kong continuously throughout the period of recording. She did not take her first trip abroad (to Australia) until 4;04. She was cared for primarily by her maternal grandmother who spoke Cantonese and ChiuChow and a Filipino domestic helper, Belma, who spoke English and some Cantonese. She started attending a local Chinese kindergarten at 2;6 in the morning and in addition, attended an English-speaking kindergarten in the afternoon from 3;02. She continued to attend both schools until 5;01. The different kindergartens are each monolingual in the respective language.

While the circumstances are similar overall to those prevailing in Timmy's case, Sophie's different personality and character lead to differences in the data. While her brother was reserved and passive, she was typically lively and talkative in recording sessions, even becoming argumentative as she grew older. In addition, being cared for primarily by her grandmother and remaining in Hong Kong exclusively during her preschool years means that the predominance of Cantonese input is even greater in her case than in Timmy's. This is reflected in the fact that while Cantonese recordings are available from age 1;06.00, she only began to use English productively at around 2. While in many respects her development recapitulates that described for Timmy (such as wh in situ, null objects and prenominal relative clauses: see Yip & Matthews 2000), her English also shows some forms of transfer which are not evident in Timmy, such as extension of the verb give to permissive and even passive usages.

Since her grandmother speaks Chaoyang (Chaozhou) dialect as well as Cantonese, Sophie developed some passive knowledge of this dialect. She learnt that producing occasional phrases in Chaozhou was a source of amusement, but did not produce full sentences. There is also the possibility of syntactic influence from Chaozhou, for example in the ordering of double objects.

The parents kept a diary of Sophie's utterances to supplement the audio and video-recording data. The diary continued beyond age 4, when regular recording ceased, in order to follow up some of the features.

The format of the English and Cantonese data is as described for Timmy in the first installment of the Hong Kong corpus: the grammatical category labels for the English corpus are based on the MOR grammars for English in the CHILDES Windows Tools, while the Cantonese data were tagged using a program developed by Lawrence Cheung on the basis of the grammatical categories used in the Hong Kong Cantonese child language corpus (Cancorp) created by Lee et. al. (1996), which contains eight monolingual Cantonese speaking children's data from 1;05 - 3;08. There are three tiers with the main tier showing Cantonese in the JyutPing romanization, with Chinese characters and grammatical categories shown on separate tiers.

A total of three sample audio-linked transcripts and two video-linked transcripts featuring Sophie's speech at 2;05 are available for access via the CHILDES archive. The three audio-linked transcripts feature Cantonese and English as well as some Cantonese-English code-switching. Two of the audio-linked transcripts have video-linked counterparts. The shorter of these transcripts has a video-linked counterpart, with a sound track that is less clear than in the audio-linked one. In the shorter video excerpt (3:00) sound quality may be improved by adjusting the balance to turn down the right channel. The video-linked files feature each language respectively as the base language as well as code-switching in the longer one (4:13).