The "Make Our Streets Safe Again Act" (MOSSA Act) aims to reduce crime and disorder by addressing homelessness, mental illness, and substance abuse through various federal actions. It directs the Attorney General and the Secretary of Health and Human Services to promote civil commitment for individuals with mental illness who pose risks or cannot care for themselves, and to assist states in implementing flexible commitment and treatment standards. The bill mandates that federal agencies, including the Departments of Justice, Health and Human Services, Housing and Urban Development, and Transportation, prioritize discretionary grants for states and municipalities that enforce prohibitions on open illicit drug use , urban camping and loitering , and urban squatting . Priority is also given to jurisdictions that address individuals with serious mental illness or substance use disorder through assisted outpatient treatment or civil commitment, and those complying with sex offender registration obligations. Federal resources are to be redirected, with the HHS Secretary ensuring grants fund evidence-based programs and explicitly excluding "harm reduction" efforts that facilitate illegal drug use. The Secretaries of HHS and HUD are directed to increase accountability in homelessness assistance programs by ending support for "housing first" policies and requiring recipients to mandate substance abuse or mental health services as a condition of participation. The legislation also strengthens enforcement against illicit activities and protects vulnerable populations. The Attorney General is tasked with reviewing and taking action against recipients of federal housing assistance that operate drug injection sites or permit illicit drug use, while the HUD Secretary must prevent sex offenders from being housed with unrelated children in federally funded programs.