This paper integrates and reinterprets new data from a set of experiments in the authors' lab in order to tease apart many of the factors thought to influence bilingual processing. Specifically it combines data from studies investigating age of immersion (AoI), manner of acquisition (MoA), proficiency and context of bilingualism to (1) investigate the organization of the bilingual mental lexicon and (2) determine the nature of the interaction between bilingualism and cognitive control. It suggests that a naturalistic MoA promotes the integration of the bilingual lexicon, and that an early AoI per se is somewhat less important (though it tends to lead to a more naturalistic MoA). Further, bilinguals with an integrated bilingual lexicon (i.e., naturalistic learners) only develop cognitive control advantages if they are in a dual-language environment.