A growing consensus sees the bilingual lexicon as an integrated, nonselective system. However, the way bilingual experience shapes the architecture and functioning of the lexicon is not well understood. This study investigates bilingual lexical-semantic representation and processing employing written translation priming. We focus on the role of active exposure to and use of the second language (L2)--primarily operationalized as immersion. We tested 200 highly proficient Spanish--English bilinguals in two groups differing in their societal language (immersed vs. nonimmersed) and amount of L2 use. L2 proficiency was controlled across participants, allowing us to disentangle its effects from those of L2 use. Overall, however, the immersion's impact on our data was minimal. This suggests a ceiling effect for the influence of active L2 use on bilingual lexical functioning when L2 development is maximal. The present data provide relevant insights into the nature of the bilingual lexicon, informing developmental models.