School Safety and Mental Health Services Improvement Act of 2018 This bill amends the Elementary and Secondary Education Act of 1965 to allow state and local educational agencies to use certain federal funds for activities related to school safety, including: (1) infrastructure improvements to prevent, mitigate, or respond to incidents of school violence; and (2) professional development for school personnel in mental-health awareness, crisis response, and other programs designed to reduce and prevent school violence. The bill also amends the Public Health Service Act to expand the programs for which the Department of Health and Human Services may provide financial support to assist local communities in helping children deal with violence. Such programs may include those designed to provide mental-health and substance-use disorder assessments, crisis-intervention training, counseling, treatment, and referral. The President must convene an interagency task force to address school safety.