Supporting Adopted Children and Families Act of 2019 This bill requires the Administration for Children and Families (ACF) to award grants to states for post-adoption and post-legal guardianship mental health services. Specifically, grants may be used to implement statewide direct service programs such as educational support or counseling to aid adoptive parents and families in addressing common behavioral health issues among adopted children. Grants also may be used for activities such as peer-to-peer mentoring, crisis intervention, program evaluation, policy development, and research, among others uses. The ACF must grant only one awards per state, or state-designated entity, and preference must be given to eligible entities that partner with a state's mental health agency and have demonstrated success at increasing adoption and legal guardianship competency.