In this paper, drawing from data from several experiences and studies in which I have been involved in Mexico, I reflect on the constraints and inertia of classroom cultures, and the barriers to successful, meaningful and transformative technology integration in mathematics classroom. I focus on teachers as key players for this integration, calling for more teacher involvement in both professional development, and as co-constructors and collaborators in the design of technological implementations and resources. [For complete proceedings, see ED581294.]