This study examines gender marking in the Spanish of Basque-Spanish bilingual children. We analyze data collected via a production task designed to elicit 48 DPs, controlling for gender of referents and for number and types of morphological cues to grammatical gender. The goals were to determine the extent to which participants rely on biological cues (female referent =>FEM gender, male referent =>MASC gender) and morpho-phonological cues (-a ending =>FEM, -o ending =>MASC, others =>MASC or FEM) to assign gender to pseudowords/novel words; and whether bilinguals’ language dominance (Spanish strong/weak) has an effect. Data were collected from 49 5- to 6-year-old Spanish-speaking children—28 monolingual L1 Spanish (L1Sp) and 21 Basque-dominant (L1 Basque-L2 Spanish) bilinguals (BDB). Results reveal a general preference for MASC gender across conditions, especially in BDB children, who produced masculine modifiers for 83% of items, while the L1Sp children did so for only 63% of items. Regression analyses show that for both groups, morphological cues have more weight than the nature of the referent in participants’ assignment of gender to novel words, and that the L1Sp group is more attentive to FEM morphological markers than the BDB group, pointing towards the existence of differences in the strength of cue-patterns for gender marking.