This paper analyses to what extent the decision to start exporting may be subject to spillovers of the internationalisation behaviour of other (foreign and domestic) firms. We distinguish between two possible channels: effects on productivity and effects on the perceived level of sunk costs of exporting. For both channels, we consider geographical and activity or industry-based linkages between firms. For a sample Belgian firms we find evidence of significant spillovers on productivity as well as productivity-independent spillovers on the decision to start exporting. Spillovers seem more substantial in the geographical dimension than in terms of competitor, client or supplier links, except for the impact of multinationals on the productivity of domestic firms.