This study examines heritage speakers of Spanish in The Netherlands regarding their production of gender in both their languages (Spanish and Dutch) as well as their gender assignment strategies in code-switched constructions. A director-matcher task was used to elicit unilingual and mixed speech from 21 participants (aged 8 to 52, mean = 17). The nominal domain consisting of a determiner, noun, and adjective was targeted in three modes: (i) Unilingual Spanish mode, (ii) unilingual Dutch mode, and (iii) code-switched mode in both directions (Dutch to Spanish and Spanish to Dutch). The production of gender in both monolingual modes was deviant from the respective monolingual norms, especially in Dutch, the dominant language of the society. In the code-switching mode, evidence was found for the gender default strategy (common in Dutch, masculine in Spanish), the analogical gender strategy (i.e., the preference to assign the gender of the translation equivalent) as well as two thus far unattested strategies involving a combination of a default gender and the use of a non-prototypical word order. External factors such as age of onset of bilingualism, amount of exposure and use of both languages had an effect on both gender accuracy in the monolingual modes and assignment strategies in the code-switching modes.