New Zealand research two decades ago led to SIDS prevention campaigns. The ""Back to Sleep"" campaigns substantially reduced mortality. However, SIDS remains the leading cause of death in the post neonatal age group. SIDS now predominantly affects the most disadvantaged sections of the community. In Aotearoa the most disadvantaged are Maori. We propose a nationwide case-control study of all sudden unexpected infant deaths. Cases will be enrolled through the coronial offices. The controls will be matched by ethnicity, obstetric hospital, date of birth and gender. As a first step however, we propose a feasibility study in Northland and Auckland. The aims of the feasibility study are (i) to confirm that the SUDI referral advisor can see a high proportion of the cases, and (ii) that the research interviewers can contact and engage the controls, particularly those that are ""hard to reach"". This includes consultation with Maori communities to develop culturally appropriate research interview protocols.