We investigate whether the practice of voluntarily appointing two audit engagement partners is associated with audit quality and audit fees relative to appointing one partner and in which ways. Using a sample of publicly-held Finnish and Swedish firms listed in the Nasdaq OMX Exchanges, we find evidence that joint engagement partners are associated with higher earnings quality, but also with higher audit fees. Moreover, we show that joint engagement partners being co-located in the same office further increases both earnings quality and audit fees. In general, our findings indicate that the ‘four eyes principle’ benefits users of financial statements whether arising from the scrutiny of two jointly responsible engagement partners or from that of two audit firms. Furthermore, given the renewed regulatory interest in the issue of audit quality and joint audits, our evidence should be of interest to policy makers.