Objective To examine the effect of mandated state health care–associated infection (HAI) reporting laws on central line–associated bloodstream infection (CLABSI) rates in adult intensive care units (ICUs). Data Sources We analyzed 2006–2012 adult ICU CLABSI and hospital annual survey data from the National Healthcare Safety Network. The final analytic sample included 244 hospitals, 947 hospital years, 475 ICUs, 1,902 ICU years, and 16,996 ICU months. Study Design We used a quasi‐experimental study design to identify the effect of state mandatory reporting laws. Several secondary models were conducted to explore potential explanations for the plausible effects of HAI laws. Principal Findings Controlling for the overall time trend, ICUs in states with laws had lower CLABSI rates beginning approximately 6 months prior to the law's effective date (incidence rate ratio = 0.66; p < .001); this effect persisted for more than 6 1/2 years after the law's effective date. These findings were robust in secondary models and are likely to be attributed to changes in central line usage and/or resources dedicated to infection control. Conclusions Our results provide valuable evidence that state reporting requirements for HAIs improved care. Additional studies are needed to further explore why and how mandatory HAI reporting laws decreased CLABSI rates.