When a parent seeks to have the custody order changed, it is his/her burden to show the court why it should be changed. The court follows the notion of, "if it isn't broke, don't fix it." This is based on the idea that stability is best for the child unless you can show that there is something in the environment that will harm the well being of the child. This is not as simple as it may seem. You will have to show that your home will be better than the home of the custodial parent (not just as good).  To do this you must show that there has been a substantial change in circumstances and that it is in the child's best interests to make the change you are proposing. If the two homes are thought to be equal, then custody will stay as it is. Remember, a temporary or "pendente lite" custody order is not a final order. You would not be required to show a substantial change in circumstances to have temporary custody changed in the "permanent" custody order.

A child at least 16 years of age can seek a change in custody on his/her own. However, it will be the minor's burden to prove that a change of custody would be in his/her best interests at this time.

The court that made the original custody and visitation order retains jurisdiction to decide modification unless the parties and child no longer have close ties to the court and the court surrenders its jurisdiction. However, the court with original jurisdiction may refuse to hear the custody case if a child has been wrongfully taken from another state or taken without the consent of the person entitled to custody.

What qualifies as a substantial change in circumstances?

Here are some examples:

Geographic move. If a custodial parent makes a significant move, or the move will seriously disrupt the stability of the child's life, the move may constitute a changed circumstance that justifies the court's modification of a custody or visitation order. Some courts switch custody from one parent to the other, although the increasingly common approach is to ask the parents to work out a plan under which both parents may continue to have significant contacts with their children. If no agreement is reached, courts in some states will permit the move unless it is shown that the child will be adversely affected. In other states, courts will carefully examine the best interests of the child and make a decision about which parent should have custody.

Change in lifestyle. Changes in custody or visitation orders may be obtained if substantial changes in a parent's lifestyle threatens or harms the child. If, for example, a custodial parent begins working at night and leaving a nine-year-old child alone, the other parent may request a change in custody. Similarly, if a non-custodial parent begins drinking heavily or taking drugs, the custodial parent may file a request for modification of the visitation order (asking, for example, that visits occur when the parent is sober, or in the presence of another adult). What constitutes a lifestyle sufficiently detrimental to warrant a change in custody or visitation rights varies tremendously depending on the state and the particular judge deciding the case.