In the great melting pot that is modern American society it is not un-common to see a child speaking one version of Chinese to parents, another version - to grandparents (when they are in the country), Spanish to the babysitter and English to everybody else. Children are like sponges and they do absorb a lot of information. The main rule in this situation is separation of the languages - any given language is spoken only by a certain person or at a certain location. This is the main idea of immersion, as it was described in one of the posts. Most of the times in a young healthy well adjusted child there is almost no resistance towards multiple language acquisition and the possibility of negative effects is low.

Usually children can start preferring English to any other language when they enter do the school. Taking in consideration that after 5 years of age most of the language acquisition is happening outside the house (school, TV, extracurricular activities) children will begin to switch their primary language from the one spoken at home to English. It will take a lot of effort and hard persistent work to keep the "home" language alive, but still children will think in English and will start constructing phrases at home
as a translation from English. My usual rule of thumb - it is a presence of the grandparents or other constantly present authoritative adult in a household, which will determine the preservation of the "home language".

Some populations are incredible in maintaining their language while being active in American society for generations. My favorite example is the descendants of the so called "White" Russian immigration. Those families left Russia after the Revolution (1917) and the Civil War, and many of their grandchildren and great-grandchildren still do speak clear fluent classical Russian.

 For an immigrant child, the one, who just arrived to the country, the immediate concern is the assimilation and acception by his/her peers. It will take a lot of self-esteem and internal discipline both in a child and his/her parents, in order to maintain and further develop "home" language. For some children and teenagers maintaining their native language means maintaining their immigrant status, which can prevent them from blending in. They can refuse to go out in public with their non-English speaking relatives and will agree to respond to parents only in English. It is also a very convenient reason for a fight with parents (and those teens are notorious in finding our soft spots). Add to this constant battle the fact, that for the working parents, who do speak English all day at work, it is also very hard to "switch" languages at home, - and the native language can
almost disappear in one generation.

It is interesting, that when those children do grow up and became parents themselves, some of them want to raise their own children... in their native culture! I can see the difference in Parent's language - in 2-3 years their Russian re-appears and improves dramatically!

 In addition to the above stated issues, adopted children do have their special needs and problems.

First of all, it is the whole issue of the post-traumatic stress syndrome. You can visit Dr. Boris Gindis site and he has a lot of very good materials about it. It is a well known fact, that for many children even hearing Russian language is frightenening and painful. Some parents do report that children as young, as 18 months of age, would start crying unconsolably when they will hear Russian speech even while still in the country. Remarkably enough, they will calm down very quickly, when spoken to in English. We can see it in the office too.

Recently I had to evaluate a 3 yo girl, adopted 1 year prior to this. From the very beginning, in the waiting room, she became agitated and started crying, when my office staff greeted her in Russian. When her grandmother tried to reason this toddler, telling her that she (the girl) is Russian too, she responded - no, I am American! When I was taking history, I found out that this baby had problems with her sleep - both falling asleep and waking up in the middle of the night. She would have the same "nightmare" every time - she would scream "Wolf,. wolf, take away the wolf". Initially mother was not able to understand what was going on (no books with wolfs were read to this child), until one day she followed where her daughter was pointing and saw a ... Russian doll, hanging on a mirror. Soon after this doll was removed, child started sleeping more peacefully.

At the same time, one of the best wedding presents I ever received last year, was a card from one of my older adoptive sibling pair. A lot of cards from our Russian-speaking family and friends were written in English, but this one was written in Russian! Sure enough, in every word letters were alternating between both languages, but it was the effort, that counted. The girl from this pair is also famous for giving me a special complement during her recent physical, which on her request, was partially conducted in
Russian. When we finished, she told me: "Doctor, your Russian is pretty good!":-)

In the simplest case scenario maintaining Russian in a language delayed verbal child or introduction of Russian in parallel with English in delayed non-verbal toddler can lead to severe language problems and confusion. In more serious situation behavioral and emotional difficulties can develop or became worse, if they were present before. In some cases parent's insistence on maintaining Russian language can lead to a simple question: "Why those parents are keeping this language for me if they want me to stay with them
forever? Are they planning to return me back?!" And as you can understand, that would not help with neither with bonding and nor with formation of trust.

So, in whom it can be safe to keep Russian and in whom not (those lists can be very long).

The positive predictive factors will be
1. Older age adoption (middle school and up)
2. Positive attitude towards Russian language
3. Psychological maturity and health, good self-esteem
4. Age appropriate language development
5. Presence of another Russian speaking child in the family
6. Acceptance of the bilingual status by the peers
7. Possibility of language maintenance and development
8. Good language abilities.

Negative predictive factors -
1. Younger age
2. Negative or even aggressive attitude towards Russian language
3. Developmental delays
4. Psychological immaturity and instability, behavioral problems, poor self-esteem
5. Language delays with and without underlying medical problems
6. Learning problems
7. Negative attitude towards bilingual status by peers
8. Absence or inadequate language recourses.