The need for innovation in the Spanish educational system has become more evident in the wake of the last PISA reports. To find our own way to achieve better schools we "must" take advantage of what schools that managed to sustain changes over time have learnt from such a process. This paper reports on findings from an inquiry that tried to shed light on the knowledge embedded in the practices of schools commended by external advisers as they had institutionalized a recognisable dynamic of changes. In order to meet this goal, five primary, four secondary and one special education school--most of them in challenging contexts--from two different regions in Spain were studied by means of ethnographic methodologies. The results described in this paper depict the main levers for improvement shared by these schools. Important support for change processes was found in the narratives deployed about the disadvantaged context surrounding the schools and the high value of teaching in these circumstances. On the other hand, the leadership that supported the change dynamics was clearly distributed and the leaders used diverse power sources in order to tackle changing contexts. Other key factors that apparently facilitated the sustainability of change were the priority given to supportive school climates; organizational cultures that encouraged teachers to take risks and essay new ways of teaching; and the practice of innovation by adopting an emergent, unplanned, "free-flowing" pattern. These findings are discussed in the light of common issues of the recent school improvement literature such as: sustainability, organizational knowledge and learning, communities of practice and building capacity to change.