Two experiments designed to explore the acquisition of grammatical gender in French as a foreign language are reported. A sample of 270 children belonging to schools in Luxembourg realized a gender assignment task with pseudo-words which endings were either marked as feminine (-elle) or masculine (-oir) in French. Children differed in their native tongue because they were from two nationalities: Luxembourgish or Portuguese. This factor has a great interest as the similarity between L1 and L2 grammatical gender systems is a matter of debate in theoretical explanation of the ease or difficulties of a foreign language. The main results show that from third grade onward children use morpho-phonological cues to assign a gender to a pseudo-word independently of their native tongue. The didactical implications of these results are discussed. We support the idea that a better understanding of the acquisition of grammatical gender has also some broader implications for foreign-language acquisition. Apart from gender, suffixes also contain semantic information. With a focus on suffixes it is thus possible to gain a rich information about the lexical properties of a foreign language and represents thereby a way to expand the vocabulary of the learner.