Much of the emphasis on the learning of subject leaders in secondary schools is placed on what Eraut (2000) terms "organised formal learning events". This article attempts to redress the balance by focusing on the somewhat neglected area of their informal learning about the role, which is predominantly based in the workplace. It is argued that informal learning consists of three components: implicit learning, learning through experience and non-taught or deliberative learning (following Eraut, 2004). Such forms of learning can be underpinned by theoretical notions of cognitive, affective and behavioural developments. A model of work-based informal learning is proposed that also tries to incorporate the memories of relevant past and current events. It is hoped that this model might be useful as a framework for the future analysis of the learning of subject leaders. (Contains 2 figures and 3 tables.)