The main contribution of this paper is to study empirically how the horizon effect and the technological or organisational changes interact to explain the probability of being an internal trainer at the end of career. We use data from a French matched employer-employee survey on Organisational Changes and Computerisation (COI) conducted in 2006. It contains information both on employees’ knowledge transmission practices and employers’ technological or organisational changes. We find that the shorter the horizon of a worker aged 50 and over, the higher is her probability of being an internal trainer, but only in firms that did not experience any changes. In changing firms, we find the same effect provided that the older worker benefited from a training session to update her skills.