Research has shown that a bilingual cognitive advantage in young adults manifests inconsistently. The objective of the present study was to investigate the existence of a bilingual advantage in this age group, whilst looking at factors which may influence its detectability and thus contribute to explaining the variability in previous research. In order to ensure that all bilinguals had spent a period of time speaking their second language in its natural environment, bilingual exchange students were recruited. This bilingual group was tested alongside a monolingual exchange group and a monolingual control group who had not been on exchange. One hundred participants were administered a battery of tests, chosen to reflect the selective pattern of advantage in executive function found in previous research. Tests of auditory attention and attentional switching were taken from the Test of Everyday Attention battery (TEA; Robertson, Ward, Ridgeway & Nimmo-Smith, 1994), a test of mental flexibility was used from the Delis Kaplan Executive Function System (D-KEFS; Delis, Kaplan & Kramer, 2001) and in addition, the Rey-Osterrieth Complex Figure (Osterrieth, 1944) was given to participants to assess general cognitive function. Bilinguals and monolinguals performed comparably on all tests. A significant difference did however emerge between monolingual participants who had been on exchange and control participants on the D-KEFS Card Sorting task. Scores on this task were also found to diverge dependant on whether the participants were currently on, or had completed, their exchange. Finally a difference was found on the ‘Elevator Counting with Reversal’ sub-test of the TEA between participants speaking three and four languages. Possible explanations for these findings and their implications for future bilingualism research are discussed.