Early reported findings pointed to a wide range of cognitive benefits of bilingualism. Recent meta-analytic and experimental results, however, cast serious doubts on whether these reported bilingual advantages in cognitive tasks were real, especially so in young adults. This dissertation uses a multi-measure, multi-method approach to comprehensively evaluate monolingual and bilingual differences among college-aged participants. It examines the core cognitive domains of executive function (Chapter 2), conflict monitoring in cognitive control (Chapter 3), and creativity (Chapter 4). Results showed that monolinguals and bilinguals did not differ on any of five dimensions of executive function, or in conflict monitoring, as assessed by both easier and more difficult tasks and task conditions. As hypothesized, bilinguals, however, outperformed monolinguals on measures of nonverbal creativity, whereas the reverse was true for verbal creativity. Additional analyses examined the possible contributors to this difference, focusing on objectively-assessed measures of English proficiency (listening, speaking, reading, and writing), visual-spatial reasoning ability, and the creativity-related personality characteristic of Openness/Intellect. English proficiency was significantly correlated with visual-spatial reasoning in bilinguals but not in monolinguals. Mediation analyses revealed that the Intellect aspect of the Openness/Intellect subscale (but not the Openness aspect) mediated the relationship between visual-spatial reasoning and English proficiency. These findings suggest that there are complex interrelations among language use and higher-order problem-solving abilities, including enduring personality traits revolving around cognitive exploration. We conclude, that, at least for young adults, there is no uniform overall cognitive advantage conferred by bilingualism, but facility in two or more languages can beneficially influence measures of nonverbal creativity.