Proper needs of the child assessment are prepared by a psychologist or a psychiatrist, or another mental health professional, who interviews each of the parents separately, and then interviews the child twice, once in the presence of each parent. The assessor may also give the children and the parents certain common psychological tests, such as personality evaluations and parenting inventories. Most often it's only the parents who are tested. The assessor will then prepare a report which that sets out his or her observations and recommendations.

In making an order that a needs of the child assessment be prepared, the court can simply say "a report will be prepared" or it can be more detailed and discuss which person will prepare the report, when it will be finished , and who will pay for it. Most importantly, the order can identify particular issues that the assessor is to address in the report. Where a report is sought because of suspected parental alienation, the order should expressly state that the assessor is to see whether alienation is or is not happening.