This brief documents the expansion of instructional specialist staffing in U.S. public school districts. We use data from the National Center of Education Statistics' annual Common Core of Data to chart staffing trends in public school districts between 1997-98 and 2012-13. The number of instructional specialists per 1,000 U.S students doubled during that period, and the proportion of districts employing no specialists declined from nearly 20% to 7%. We suggest that specialists are poised to play a pivotal "professional sense-making" role as schools work to implement new instructional standards in the classroom. [This paper was published in "Education Researcher" v44 n6 p359-364 Aug-Sep 2015 (EJ1073976).]