This paper examines the evolution of the dairy complexes of New Zealand and Chile in the context of increasing bilateral interaction between the two countries, and their recent signing of a ‘Trans-Pacific Strategic Economic Partnership’ (TPSEP) free-trade agreement. The two economies can be said to occupy semi-peripheral positions in global markets and have, through the twentieth and into the twenty-first century, increasingly competed for market share in a range of primary product (particularly agricultural)-based export markets. Similar sets of historical processes, although variably timed, have shaped the roles of New Zealand and Chile respectively as resource peripheries, and the extent to which the two countries can collaborate for mutual benefit and transcend these roles is uncertain. In taking a sectoral approach this paper questions the compatibility of the two dairy complexes in the context of the TPSEP, and recommends further sectoral and localised studies in order to better appraise the model of ‘co-opetition’ promoted through the agreement.