The HABLA-corpus (Hamburg Adult Bilingual LAnguage) comprises data in the form of semi-structured interviews gathered in the project E11, Linguistic Aspects of Language Attrition and Second Language Acquisition in adult bilinguals (German-French and German-Italian). E11 investigated the language of adult bilinguals (2L1 speakers) who grew up in Germany, Italy or France being exposed to two languages simultaneously from birth, comparing them to advanced second language (L2) learners. In this contribution, we explain the motivation for creating the corpus and introduce the corpus design, including information about the subjects, data acquisition and labelling, quality and transcription conventions, with the purpose of providing an overview of the corpus and facilitate its use.