This article reviews the experiences, obstacles, and lessons learned from development and deployment of the México Participa e-participation platform as a case study for future platforms, both in Mexico and in transitional democracies with similar sociopolitical characteristics such as pervasive distrust of public institutions and limited civic participation. México Participa was released three months before the June 2015 midterm Mexican presidential election. Although the platform continues to operate, this article focuses on the period leading up to the election. 3,054 participants offered 336 suggestions and provided 14,033 peer-to-peer assessments. A postelection survey highlighted the need for a platform such as México Participa to be continually available to sustain citizen evaluation of government performance and to promote transparency and accountability