34 Association of Research Libraries Research Library Issues 295 — 2018 Canadian ARL libraries. It is easy to imagine a broad range of possible explanations for the US/ Canadian salary disparities, but the ARL data can do little more than eliminate some of them. For example, Canadian professionals do not have higher percentages of professional experience, PhD degrees, or supervisory positions. To be sure, there are some modest differences between the two groups: Canadians are somewhat more female (69% compared to 63% in the US), and somewhat younger (45% under 45 compared to 39% in the US). None of these differences seem likely to explain the salary differences, however. I suspect that the primary drivers are macroeconomic in nature, and outside the scope of this study. Historically Underrepresented Groups The demographic profile of historically underrepresented groups in professional positions in US ARL university libraries is frustrating in that 2015 proved to be yet another year in a series that has exhibited only excruciatingly slow improvement.3 (See Figure 1.) The Caucasian portion of the population fell in the 35 years between 1980 and 2015, but only slightly, from 88.6% to 85.1%. This metric alone can’t support the conclusion that our diversity efforts have failed. It’s always possible that without these efforts, our situation could have gotten worse! But our profession aspires to far greater progress in this area, and the 2015 data should spur commitment to redoubled efforts, or entirely new efforts, or both.