Little is known about how the experience of being bilingual and speaking two languages leads to advantages in cognitive control and flexibility (e.g., Bialystok & Martin, 2004). This study investigated productive vocabulary and knowledge of translation equivalents (TEs) as possible mechanisms underlying the bilingual advantage in cognitive flexibility and control. Spanish-English bilingual two-year-olds performed the Reverse Categorization Task (RCT; Carlson et al., 2004), which requires cognitive flexibility and control. Each child’s caregiver also completed the MCDI for English and Spanish to obtain a measure of each child’s productive vocabulary and knowledge of TEs. Correlation analyses showed that performance on the RCT was significantly correlated with productive knowledge of TEs but not cognates. These findings suggest that the experience of producing different words with the same meaning in two languages, as well as choosing between those words, may be an early mechanism underlying the bilingual advantage in cognitive control.