How early do bilingual children recognize that they have two languages? Recent case studies are as follows:-      1. One study of a Hebrew / English-speaking child at one year seven months showed that he spoke one language to one parent, another language to the other parent with clear separation. Thus children under two years of age seem to recognize one language from another.      2. A similar study of a Spanish and English bilingual child revealed that the child could switch from one language to another with accuracy at the age of one-year and eight months.      3. A case study of a German and French bilingual indicated that at two years and three months the child showed dissatisfaction when either of the parents addressed the child in other than the usual language.      4. A study of a Dutch and English bilingual aged three showed that the child would always choose the appropriate language when speaking with a monolingual person. However, with people she knew to be fluent bilinguals, she was much more ready to use both languages. The study suggests that many bilingual children tend not to mix languages when addressing monolinguals, but are aware enough of bilinguals to move between both languages when addressing them.