This study utilized a novel task design in an effort to identify the source of the second language processing advantage commonly reported in mixed language conditions, investigate switch cost asymmetry in non-balanced bilinguals, and identify task-related variables that potentially contribute to inconsistent results across studies with similar participant populations. Seventy highly-proficient Korean-English bilinguals completed modified picture naming, semantic categorization, and lexical decision tasks, as well as a cognitive control task designed to examine the potential relationship between lexical control and general cognitive control. While no significant relationship was found between lexical control and general cognitive control, several key task-related variables emerged with respect to mix and switch effects. Specifically, verbal production requirements and increased second language repetition effects significantly influenced results. Furthermore, this study revealed potential effects of semantic load as well as script differences in receptive tasks. Results from this study highlight several key variables that contribute to bilingual mix and switch effects, as well as task design-related considerations for future bilingual mix and switch studies.