The "Know Hepatitis B" campaign was the first national, multilingual communications campaign to promote testing for hepatitis B virus (HBV) among Asian Americans and Pacific Islanders (AAPIs). This population comprises fewer than 5% of the total U.S. population but accounts for more than half of the up to 1.4 million Americans living with chronic HBV infection. To address this health disparity with a national campaign, CDC partnered with Hep B United, a national coalition of community-based partners working to educate AAPIs about hepatitis B and the need for testing. Guided by formative research, the "Know Hepatitis B" campaign was implemented in 2013 with a two-pronged communications strategy. CDC used available Chinese, Korean, and Vietnamese media outlets on a national level and relied on Hep B United to incorporate campaign materials into educational efforts at the local level. This partnership helped facilitate HBV testing among the priority population.