Will My Child Become Confused if Chinese and English are Learned at the Same Time?

One of the main concerns of raising English-Chinese bilinguals is the possibility of confusing a child with two languages. A lot of parents are concerned about exposing children to both Chinese and English simultaneously. The child may get confused and not learn Chinese AND English at all. Parents are also concerned that a child would mix both languages up. When languages are mixed, there is also the worry that the child will never be proficient enough.
Children who are learning two languages will predictably mix up words and grammar (this is called Code Switching). This is also true even for children learning one language at a time. It is a part of learning to try out the mixing some words, some grammar, or even totally making up a new word with similar sound.
When children mix words and grammar up, that does not necessarily mean the child is confused. Research has found that by age 3, children can differentiate one language from the other. Sometimes they mix languages up because they just want to. To children, they probably don't care they are mixing up the languages. All that is important to them is that they are able to communicate what it is they need. If a child wants to play, the main concern for the child is being able to let other people know about this; not minding if words are mixed up and grammar is all wrong. This is not a cause for worry, as it has been found that when talking to a monolingual, kids are usually careful to communicate in the language being used.
When kids mix up English and Chinese words and grammar, parents should see the bigger picture: that is, exposing the child to Mandarin Chinese is a long-term endeavor. There is a short phase that children will really mix Chinese and English up, until eventually they are familiar with and proficient in both languages. Children will have different development rates until they learn to stop mixing languages up. Some kids will take a long time and always mix up languages. Others kids will do so only briefly. Others not at all. Research has found that usually, by mid-childhood, the child has more or less adjusted to both languages. A child will usually speak the primary language better than the secondary language. This is normal and should not be a cause for unnecessary worry.