The obvious advantage of joint physical custody is that living in both households allows a child to maintain a strong relationship with both parents. According to research, about half of all children in joint physical custody see both parents at least weekly, compared to one in 10 children in traditional custody arrangements (custodial mother, noncustodial father). "When both parents are available, children enjoy the unique guidance, discipline, and love of each parent," says Ms. Zinner. Moreover, "[c]hildren in joint custody may benefit materially, as child support is paid fully 75 percent of the time, compared to 46 percent in solo custody arrangements."

Clinical social workers working with children with access to only one parent "found they expressed their anger in both subtle and direct ways. They were more depressed, withdrawn, and uncommunicative, and had more somatic symptoms."