As real wages stagnate, racial disparities grow, and housing prices soar in cities across the US, local governments are increasingly adopting laws and regulations that aim to reduce inequalities and improve access to economic opportunity for their residents. At the same time, states are increasingly enacting laws that limit or preempt local action in these areas, often relying on a thin or nonexistent evidence base to suggest that local regulation is inefficient or overly burdensome. Paid sick time is one domain that has become increasingly subject to state preemption. Proponents of state preemption of paid-sick-days laws often cite concerns about having a patchwork of fringe benefit requirements across the state creating undue complexity for businesses and weakening the state’s economic attractiveness. Those advocating against preemption argue that local paid-sick-days laws can improve public health by slowing the spread of contagious illnesses and provide economic security to workers and their families. In this brief, we synthesize the evidence on the effectiveness of paid-sick-days laws and suggest areas in which further research could help policymakers, advocates, and the public improve local paid-sick-days laws.