There have been a number of major changes that have taken place in U.S. custody laws over the last several decades. One of the most significant trends has been a response to research that shows that children who have ongoing access to and interaction with both parents after a divorce tend to be happier, healthier, and better-adjusted than the children who spend most of their time with one parent. As a result of the growing recognition of these benefits, many states have now enacted custody guidelines designed to encourage and promote joint parenting efforts. One example of this is the increasingly common requirement that divorcing parents collaborate on a child parenting plan. Although the specific requirements for parenting plans vary from state to state, most allow parents the opportunity to come to an agreement on parenting beliefs and practices such as conduct, education, discipline, rules, visitation, and other important items. In theory, the process of devising a child parenting plan helps parents come to a mutual understanding and allows them to avoid disputes and conflicts in the future.