An overview of the experience of the opening two years of an institution-wide project in introducing electronic voting equipment for lectures is presented. Eight different departments and a wide range of group size (up to 300) saw some use. An important aspect of this is the organizational one of addressing the whole institution, rather than a narrower disciplinary base. The mobility of the equipment, the generality of the educational analysis, and the technical support provided contributed to this. Evaluations of each use identified (formatively) the weakest spots and the most common benefits, and also (summatively) showed that learners almost always saw this as providing a net benefit to them. Various empirical indications support the theoretical view that learning benefits depend upon putting the pedagogy (not the technology) at the focus of attention in each use. Perceived benefits tended to increase as lecturers became more experienced in exploiting the approach. The most promising pedagogical approaches appear to be Interactive Engagement (launching peer discussions), and Contingent Teaching designing sessions not as fixed scripts but to zero in on using diagnostic questions on the points that the particular audience most needs on this occasion.