In the growing field of heritage language acquisition numerous studies have been done in the last twenty years. However, one structure that has not been studied in detail is double-que questions (DQQs) in Spanish. Therefore, this dissertation analyzes the production and comprehension of double-que questions in child and adult heritage speakers of Mexican Spanish. DQQs are structures with que ‘that’ + whphrase (e.g., what, who, where, etc.) and a verb of saying like preguntar, ‘to ask’. They are used in Spanish for indirect questions to report what was said before, as in the following example from Suñer (1991): Me preguntaron [que] [a quién] invitarás tú al concierto. tome they asked [that] [whom] willinvite you tothe concert ‘They asked me whom you will invite to the concert.’ In this example, the verb is followed by the complementizer que that antecedes the whphrase a quién ‘to whom’, forming a DQQ structure to report what was asked about the concert. This construction is not available in English. Moreover, in English, indirect questions can only be expressed with the verb ‘to ask’, while in Spanish different verbs of saying can be used, such as decir ‘to tell’, gritar, ‘to yell’, and contestar ‘to reply’. In this dissertation, participants include child and adult Mexican monolingual control groups that were compared to child and adult heritage speakers of Mexican origin. Children have been used in previous studies (e.g., Polinsky 2011) to determine incomplete acquisition and language attrition. Therefore, these groups will be compared, and this will allow us to determine whether incomplete acquisition or language attrition can explain the potentially divergent uses of DQQs. The data came from a production task, a preference task, and an acceptability judgment task. In sum, this study contributes to the little research done on DQQs and mainly on the very little research on heritage speaker children. Unlike previous studies, it uses oral production and oral comprehension tasks. Importantly, by using different groups of bilinguals, it investigates whether divergent uses of DQQs in heritage speakers are due to incomplete acquisition or language attrition.