This thesis examines New Zealand's role in and contribution to the British Commonwealth in the crucial years immediately following the Second World War. A thematic approach is taken, highlighting economic, constitutional and defence ties, as well as the less discernable links of sentiment. The premise is that the Commonwealth was essentially a paradoxical association; the juncture between independent nationhood and collective solidarity. The thesis, therefore, aims to show how New Zealand exhibited both these traits and tried to maintain some equilibrium between them. However, the latter role of the loyal Commonwealth partner increasingly prevailed in the difficult international situation of the late 1940's. Certainly, by the defeat of the first Labour government in 1949, New Zealand had strongly reaffirmed its commitment to Commonwealth unity. Confirmed sovereignty was qualified by a residual imperial focus. The various influences contributing to New Zealand's inherent support for the Commonwealth will be considered. New Zealand's commitment to the Commonwealth has to, however, be seen in the context of a changing international environment. The established independence of member states, combined with Britain's decline as a major power, ensured that the Commonwealth could not function as a unitary bloc. A bi-polar balance of power, centred on the United States and the Soviet Union was to become the predominant feature of the post-war world, and Commonwealth members had to respond accordingly. In turn, the Commonwealth itself was an elastic association and continued to evolve relative to changing circumstances, as highlighted by the impact of the independence of the Indian subcontinent. This gave greater emphasis to the Commonwealth's basis as a free association of independent nations rather than a formalised alliance. The New Zealand government's conservative, even reactionary, attitude to such developments will be discussed, showing Wellington's role as the advocate of the "Old Commonwealth". The External Affairs files of the National Archives, Wellington, provided the bulk of primary research. This was supplemented by parliamentary records, newspapers and the excellent published collections of primary sources. The extensive corpus of secondary literature also provided valuable background detail. The thematic approach taken may be at the expense of a full chronological overview, but it aims to illustrate the major comparative trends of the period.