Emergency departments (EDs) are an important potential site for public health screening programs, although implementation of such programs can be challenging. Potential barriers include system-level issues (e.g., funding and time pressures) and individual provider-level issues (e.g., awareness and acceptance). This cross-sectional evaluation of a nurse-driven, triage-based hepatitis C virus (HCV) screening program in an urban, academic ED assessed variation in nurse participation from April to November 2017. For this program, electronic health record (EHR) prompts for HCV screening were integrated into nurses' triage workflow. Process measures evaluating HCV screening participation were abstracted from the EHR for all ED encounters with patient year of birth between 1945 and 1965. Registered nurses who routinely worked in triage and were full-time employees throughout the study period were included for analysis. The primary outcome was the proportion of eligible ED encounters with completed HCV screening, by nurse. Of 14,375 ED encounters, 3,375 (23.5%, 95% confidence interval [CI]: 22.8, 24.2) had completed HCV screening and 1,408 (9.8%, 95% CI: 3.9, 10.3) had HCV screening EHR sections opened by the triage nurse but closed without action; the remainder of encounters had no activity in HCV screening EHR sections. Among the 93 eligible nurses, 22 nurses (24%, 95% CI: 16, 34) completed HCV screening for more than 70% of encounters, whereas 10 nurses (11%, 95% CI: 6, 19) never completed HCV screening. The proportion of eligible encounters with completed HCV screening was 11.0% higher (95% CI: 9.8, 12.6) for encounters seen between 7 a.m. and 7 p.m. than between 7 p.m. and 7 a.m. (27.5% and 16.3%, respectively). In conclusion, wide variation in individual nurse participation in HCV screening suggests individual-level barriers are a more significant barrier to ED screening than previously recognized. Implementation research should expand beyond questions of resource availability and procedural streamlining to evaluate and address staff knowledge, beliefs, attitudes, and motivation.