This past week, you might have noticed the many news stories about killer cats. The research study about domestic cats’ impact on nature concluded that cats kill up to 3.7 billion birds and 20.7 billion mammals every year. Did you happen to pick up that the senior author on the paper was Peter Marra of the Migratory Bird Center, a research unit of the National Zoo, and one of his cowriters was Scott Loss, also of the MBC? While we are always excited by and proud of the research output of the Smithsonian, this is an example of a scholarly article having an impact in the public sphere—i.e. beyond just the scientific community. Does that matter? How does it matter? Is there a way for the organization sponsoring that research to measure impact of research output like this? These are the kinds of questions we can finally begin to tackle with the use of altmetrics.