It is generally assumed that speakers of grammatical gender languages consider grammatical gender arbitrary, but this assumption has never been tested. Research shows that the grammatical gender of nouns can affect perceptions of the masculinity or femininity of the noun's referent in speakers of languages with masculine and feminine noun classes. However, bilingualism facilitates the development of lexical arbitrariness awareness, and could therefore affect awareness of grammatical gender arbitrariness. This study then compared three groups of young adult speakers of a grammatical gender language: monolinguals, early bilinguals, and instructed second language learners. Participants evaluated the gender assignments of 25 nouns of entities (animals, abstract concepts, natural kinds, and artefacts), and answered open and closed questions about grammatical gender. Participants considered grammatical gender as semantically motivated and mostly related gender assignments to perceived masculine or feminine connotations of referents. Knowledge of an additional grammatical gender language was linked to increased awareness of the arbitrariness of first language gender assignments in both early bilinguals and later instructed learners. It is argued that grammatical gender awareness deserves further investigation. Knowing more than one grammatical gender language can increase awareness of grammatical gender arbitrariness. Implications are discussed for language teaching and language reform.