The scale-up of malaria control interventions in Papua New Guinea (PNG) resulted in a reduction in the nationwide prevalence and incidence of malaria between 2008 and 2015. However, this effect has not been uniform across the country and considerable heterogeneity in transmission exists in different areas, despite a standardised approach to the implementation of the control measures. To better understand the characteristics and determinants of residual malaria transmission in this setting, we conducted: (i) prevalence studies to confirm the magnitude of residual malaria at the time of the study, (ii) vector studies to characterize the local vector population abundance, composition and behaviour, (iii) human behaviour, in order to understand what behaviour renders which population groups susceptible to residual transmission, and (iv) the establishment of a clinical surveillance system linked to geo-referenced village locations in order to validate a routine system for identifying focal areas of transmission. Some of the results from these studies will be discussed.