This is the first attempt to profile the heritage speakers of an endangered spoken-only variety of Vlach Aromanian in Greece. Neither the variety nor its speakers has been investigated before; hence, the study also aims at evaluating the exact state of endangerment of the Sirrako variety, as this is revealed by the language practices and skills of its bilingual speakers. To this aim, a background questionnaire was developed and administered to 60 bilingual speakers of Vlach Aromanian and Greek including questions on the age of onset of exposure to both languages, early home language practices, current language practices (orality and literacy) and attitudes toward the heritage and majority language. Significant variation in language practices, literacy skills, oral input and current competence across three generations of speakers was identified with a substantial decline in heritage language competence in younger bilinguals, verifying our claim of the endangered state of Vlach Aromanian.