The Pacific Identity and Wellbeing Scale (PIWBS: Manuela & Sibley, 2013) is a culturally appropriate, self-report measure for Pacific peoples in New Zealand. It is an integration of Western psychological theory and indigenous, Pacific concepts of the self, ethnic identity and wellbeing. In this thesis, I present five studies that extend upon the PIWBS model and apply it in a research context. In Study 1, I conduct a novel, top-down factor analytic method to show how the different factors of the PIWBS are hierarchically related to each other. The resulting model highlights how facets of Pacific identity and wellbeing can be understood at different levels of abstraction and specificity. In Study 2, I develop an additional subscale of Cultural Efficacy to assess the extent to which one feels they are able to participate within a Pacific cultural context. Confirmatory Factor Analysis provides evidence of a six-factor model and subsequent analyses show how the PIWBS factors are associated with behaviours, language confidence and health. In study 3, I conduct a multi-group confirmatory factor analysis to provide evidence that the model-fit indices of the PIWBS hold for separate Pacific groups. The results indicate that the tool can be used for specific Pacific groups. A further MANCOVA analysis shows no significant differences between four major Pacific Nations groups in New Zealand, except for differences in the factor assessing Religious Centrality and Embeddedness. The next two studies show how the PIWBS can be applied in a research context and also provide evidence of convergent validity. Study Four explores differences in familial wellbeing between mono-ethnic and multi-ethnic Pacific peoples. This finding is replicated in an independent sample and shows how differences in wellbeing and self-esteem measures are explained by differences in warmth towards the Pacific group more generally. Study Five tests an identity buffering hypothesis across two independent samples, and shows that high ethnic identity buffers the effects of perceived discrimination on various measures important to the overall wellbeing of Pacific peoples. The analyses suggest that ethnic identity is a protective factor for Pacific peoples. The implications of the PIWBS are discussed in terms of its contribution to advancing both psychological and Pacific research. In addition, the underlying theoretical basis of the PIWBS is used to discuss how the integration of both psychological and Pacific knowledge can be used to establish directions toward Pacific psychologies.