L3 acquisition has begun to attract the attention of many scholars in recent years. Heritage contexts are especially fruitful areas to understand how linguistic and nonlinguistic mechanisms interact with one another. The current study focuses on L3 English acquisition of object pronouns with L1 Turkish, L2 German speakers. We seek to find out whether the speakers could produce object pronouns accurately, whether L3 English proficiency has any effects on their acquisition, and finally, whether all object pronouns are acquired in the same way. Data for this study come from a corpus consisting of written and oral productions of 167 participants, who were students in four distinct grades, namely 5th, 7th, 10th and 12th graders at different schools in Berlin, Germany. The results reveal that participants were highly meticulous in their object pronoun use. Also, no clear L1 effect was observed, while L2 impact is implied. Lastly, proficiency and linguistic features are noted as significant factors that have an impact on L3 acquisition.