For a number of years the writer worked for a large rural Local Authority in England. During this time several schools were trained in the Philosophy for Children approach and yet very few were able to sustain this innovation. Teachers are the agents of change in the classroom (Hargreaves 1994; Stenhouse 1975) and therefore the writer believes that it is vital to understand ‘the considerations which bear upon curricular action’ (Stenhouse 1975, p. 111) when teachers are attempting to implement P4C. This research set out to test the veracity of Leat’s (1999) claim that teacher efficacy (i.e. teachers’ beliefs about their ability to positively influence student outcomes) … is a measure of the chances of implementing change’ (p. 399). The study employed teacher interviews to examine the factors which teachers perceived to determine the implementation of P4C in their own classrooms.