The dissemination and sustainability of many health-care IT projects in Quebec have hardly been influenced by their evaluation, even when the evaluation was participative, pluralist, comprehensive, formative, and user-focussed. This article aims to improve our understanding of why that has been the case and to suggest courses of action and reflection. Human and organizational factors and other factors related to the evaluation itself are considered. To increase the impact of evaluation on project outcomes, the authors recommend knowing the project better, adding to the action plan usually intended to promote knowledge and learning, and further developing frameworks for integrating practices and theories to improve our understanding of the conditions for their use in action.