The best interests of the child refers to the factors most courts consider when making decisions on child custody and visitation rights.

These factors may include the needs and circumstances of the child (happiness, security, mental health, emotional development, educational opportunities, special needs, siblings, religious and cultural considerations, continuity and stability, child’s wishes) and the circumstances of the parent or caregiver (relationships, living arrangements, history of abuse, mental health, physical health, financial resources, substance abuse).

There is generally a presumption that it is in a child’s best interests to have a relationship with both of the child’s biological parents—unless one or both of the parents are shown to be unfit parents.

In Montana, the 'best interests of the child' standard is the guiding principle for courts when making decisions regarding child custody and visitation rights. This standard is codified in the Montana Code Annotated (MCA) under Title 40, Chapter 4, Part 2. The factors considered by the court include, but are not limited to, the child's wishes, the emotional ties between the child and parents or caregivers, the child's adjustment to home, school, and community, the mental and physical health of all individuals involved, the stability of the child's home environment, and the presence of any domestic violence. Montana law also recognizes the importance of maintaining frequent and continuing contact with both parents, provided it is in the child's best interest and the parents are fit. If a parent is deemed unfit due to reasons such as abuse, neglect, or substance abuse, the court may limit or deny custody or visitation rights to protect the child's welfare.