In 2006, Rwanda began implementing an Outcomes Based Education (OBE) lower secondary science curriculum that emphasises a student-centred approach. The new curriculum was designed to transform Rwandan society from an agricultural to a knowledge-based economy, with special attention to science and technology education. Up until this point in time the implementation of the intended curriculum has been barely researched and is poorly understood. Thus our primary research question is, "To what extent is the intended national curriculum actually implemented in Rwandan schools?" To explore this question, we examine the implementation of the new science curriculum in three socially and environmentally diverse schools. Using the Rogan-Grayson curriculum implementation model as a theoretical framework, we explore the link between the level of curriculum implementation and the schools' capacity to innovate. We do this through the observation of lessons and school environment and by means of structured interviews with school administrators, teachers and students. As far as the observed lessons are concerned, there is a wide variation in levels of lessons both within and between schools. With the exception of 3 out of 20 observed lessons, almost none of the lessons throughout the three schools showed any appreciable achievement of the curriculum objectives. It appears that there is only a tenuous link, if any, between the implementation level and the capacity of the school to innovate. Our research explores implementation in a unique environment--in a country recovering from genocide and where the language of instruction has changed from French to English. In the context of international development in education, one critical question has emerged from these findings: under what conditions can the teaching as intended by an OBE curriculum become routine for teachers? A possible answer to this question is discussed. The common and specific challenges to Rwandan schools with respect to the implementation of new curriculum are also discussed and some proposals are made to overcome these specific challenges.