Candidate selection shapes descriptive representation in important ways; you cannot be elected without first being selected. Unravelling opaque candidate selection processes is therefore critical to understanding descriptive representation and political parties’ electoral strategies. Drawing on a new dataset of New Zealand candidacies from 1996 to 2020, we demonstrate variation in candidacy patterns across parties, ethnic groups, and time. We show that both the centre-left (Labour) and centre-right (National) have increased the ethnic diversity of their candidate slates over time, although Labour’s overall share of non-majority candidates is higher than National’s. Both parties have primarily used the party list, not district candidacies, to achieve diversification. This approach leads to some volatility in representative diversity, in part due to list composition practices that prioritise incumbents and cluster ‘ethnic’ candidates. Thus, while New Zealand candidate slates show notably high diversity by international comparison, non-majority candidates can nonetheless find themselves in electorally vulnerable positions.