This document discusses evaluating e-petition systems by examining users' self-efficacy. It defines self-efficacy as one's beliefs about their capabilities, and distinguishes between computer self-efficacy and political self-efficacy. The author proposes that integrating measures of self-efficacy into the evaluation of a new e-petition system called EuroPetition can provide insights into why some concerned citizens do not engage or drop out of the petition process. Data on users' self-efficacy would be collected throughout the system's design, development and use to understand factors influencing participation.