Empirical research in the field of bi-/multilingualism has shown that the acquisition of two (or more) languages during childhood is significantly influenced by the sociolinguistic experience of each individual, namely by the quantity and the quality of language exposure to the target languages (Unsworth 2016a). In fact, the heterogeneity of sociolinguistic contexts in which bilingual acquisition takes place leads to variation in the quantity and quality of the input to which bilingual children are exposed on a daily basis, which, in turn, originates individual variation in the levels of language development in the languages under acquisition, mainly, in the minority language (also known as heritage language/HL; cf. Montrul 2016). In order to assess the effect of language experience on bilingual development, studies usually resort to sociolinguistic questionnaires, which allow the researcher to outline the sociolinguistic profile of the subjects under analysis, as well as to obtain crucial information about predictive variables of bilingual development (see Unsworth 2019). In this paper, we present a sociolinguistic questionnaire, in Portuguese, developed for the collection of data on the sociolinguistic experience of bilingual children, between the ages of six and ten, with a migration background – the Questionário Sociolinguístico Parental para Famílias Emigrantes Bilingues (QuesFEB). This parental questionnaire, intended for researchers who conduct studies in the field of heritage bilingualism, has as its main objective the collection of biographical and sociolinguistic information not only for the detailed characterisation of the context in which bilingual children acquire the heritage language, but also, and mainly, for the quantification of their language experience in the target language, enabling the assessment of the effect that variables related to input quantity and quality have on that language. Besides providing a detailed description of the content of the sections that compose the QuesFEB, we will present, in detail, the method of codification and calculation of four key variables that have been found to be predictive of HL development, namely: (i) current quantity of HL use (i.e., input and output) in the household; (ii) quantity of cumulative exposure to the HL in the household; (iii) quantity of HL use (i.e., input and output) with migrant grandparents who are native speakers of the language of origin; and (iv) richness of the language exposure to the HL.