This volume of The Reference Shelf looks at the challenges facing police, from funding and staffing shortages to the influence of political polarization. The changing public perception of police and calls for reform are also examined. The controversial "Defund the Police" and "Black Lives Matter" protests against police brutality are covered, while other articles explore policing and immigration enforcement, mental health and de-escalation training, and law enforcement during civil rights protests. Also explored are the ways in which the onset of COVID-19 has changed policing and how these changes might impact the future of policing after the pandemic. --