The recording sessions of Simon and Leo´s linguistic production from the FerFuLice corpus began in February 2000. The data we have collected cover the age range of 1;01 to 6;11.

In the recordings we followed the procedures specified in the literature on monolingual and bilingual acquisition (Slobin 1985, De Houwer 1990, López Ornat 1994, McDaniel et al. 1995, Thornton 1996, Rice et al. 1999, Bel 2001, among others).

A total of 178 sessions were recorded on videotape and DVD, of which 117 are in an English context (where the children interact with an English interlocutor such as one of the researchers or their mother) and 61 in a Spanish context (i.e. with a Spanish interlocutor such as one of the researchers or their father). The Spanish recordings were made at intervals of 2-3 weeks until age 3;00 and then once a month after that. The English recordings were sometimes made more frequently, but the sessions are usually much shorter and recorded on consecutive days. These periodic recordings were interrupted for approximately two months in the summer when the family travelled to the United States.

During this time, recordings were made by the parents so that continuity was maintained. Simon and Leo were recorded in naturalistic settings, usually at home, and appear together in the majority of the sessions. They were mostly engaged in normal play activities with their parents and the researchers.

The transcriptions of the 178 sessions included in the FerFuLice corpus were codified in the CHAT system for the CHILDES database (MacWhinney 2000).

The Spanish sessions were transcribed by the Spanish research team directed by Raquel Fernández Fuertes (University of Valladolid), and the English sessions were transcribed by the Canadian research team directed by Juana M. Liceras (University of Ottawa). Both teams have also collaborated in the transcription of some bilingual sessions in which three translation tests are included.

Inventory: information for each session (MLUw, number of utterances, etc.).

CHAT format: information regarding the transcription procedure (headers, codes, etc.).