Technologies for social inclusion in Latin America are a recent manifestation of grassroots innovation movements whose global activities go back to appropriate technology in the 1970s and earlier. Common to these movements is a vision for innovation processes more inclusive towards local communities in terms of knowledge, processes and outcomes. In this article Adrian Smith, Mariano Fressoli and Hernán Thomas draw a comparison between movements for technologies for social inclusion now and appropriate technology in the past. Analysis reveals three enduring challenges for grassroots innovation: attending to local specificities whilst simultaneously seeking wide-scale diffusion; being appropriate to existing situations that one ultimately seeks to transform; and, working with project-based solutions to goals (of social justice) whose root causes rest in structures of economic and political power. Each challenge effectively frames grassroots innovation differently, and responses generate valuable forms of knowledge production: grassroots ingenuity; grassroots empowerment; and structural critique. Overall, these movements contribute valuable plurality and reflexivity to innovation policy and politics.