This is a particularly interesting outbreak investigation of mumps in Texas. California residents may remember the 2015 measles outbreak starting in a “California amusement park” (Disneyland). During that outbreak, we performed a large number of measles/mumps/rubella (MMR) immunity tests on concerned and potentially exposed individuals. The most common reason for us to re-vaccinate with the MMR vaccine was not because of lack of measles protection but was instead inadequate mumps immunity. In fact, in 2014 there was a significant mumps outbreak in the National Hockey League. People born between 1970 and 1992 represent a group with only partial protection against mumps and are most at risk. A single shot was common at the time, and two doses did not become standard until the mid-1990s