The influence of niobium and vanadium additions on the precipitation behaviour in a 24Cr-18Mn-1N austenitic stainless steel is characterised during ageing at temperatures from 800 to 1100 °C. Niobium demonstrates a tendency to stabilise the cubic MX-type precipitates, whereas vanadium encourages the formation of hexagonal close-packed M2X-type precipitates. Vanadium, furthermore, promotes formation of M2X-type precipitates by the discontinuous cellular precipitation (DCP) reaction. The presence of sigma phase and a high frequency of austenite twinning occur in association with the DCP reaction during ageing. This behaviour, together with the influence of niobium and vanadium, is used to understand the driving force for boundary migration during the DCP reaction.