There is growing interest among communities in deploying municipally-run broadband Internet to deliver high-speed Internet access to their residents. These public networks often operate alongside private incumbent Internet networks, which may have substantial effects on the competitive landscape. The research design exploits variation in cities that have a municipal electric utility (MEU), which reduces barriers to entry for municipal providers, and state-level regulation, which restricts public entry into broadband markets. Using these market differences, I investigate whether incumbents offer higher speeds to deter entry or underinvest in speed due to crowding out. My estimates indicate that the presence of an MEU is associated with lower maximum upload and download speeds offered by private cable and DSL providers. Additionally, the presence of an MEU crowds out firms at the entry stage. In states where municipal entry is made more difficult by regulation, these effects disappear. Therefore, restrictive regulation of municipal broadband has a non-trivial anticompetitive effect.