Eye tracking data are routinely collected during Web survey usability testing at U.S. Census Bureau. While oculomotor activities are informative for inferring respondent performance of completing Web survey, challenges remain to establish performance indicators using eye tracking data. This talk will highlight some of the challenges faced when incorporating eye tracking into usability studies of electronic surveys; and will explore interpreting results with respect to the other common usability metrics of effectiveness, efficiency, and satisfaction. Examples of how results can support findings will be presented. In addition, the talk will touch on both the technical and the methodological challenges that may be encountered when using eye-tracking technology on mobile devices.