Moms Matter Act This bill establishes two grant programs to address maternal mental health conditions and substance use disorders, with a focus on racial and ethnic minority groups. First, the Substance Abuse and Mental Health Services Administration must award grants for maternal behavioral health services. Eligible grantees include state, tribal, and local governments; health care providers; and organizations that serve pregnant and postpartum individuals. Second, the Department of Health and Human Services may award grants to grow and diversify the maternal mental and behavioral health workforce by establishing or expanding schools and training programs.