Introduction Transnational and organised crime is supported by complex and multilayered networks that are mobile, well-resourced, and strategically coordinated, enabling them to operate across international borders (Dandurand 2007, Le Mière 2011) and making them a major threat to global security (Goldsmith and Sheptycki 2007, UN Office on Drugs and Crime (UNODC 2016). Many argue that such crimes are primarily opportunistic, facilitated by global connectivity and the potential for large profit margins (Madsen 2009). Dialogue among scholars and practitioners about transnational and organised crime in Pacific Island Countries and Territories (PICTs) often only scratches the surface of the multifaceted nature of the threat posed to many small countries in the Pacific. PICTs are characterised by large geographic areas largely of ocean, porous maritime borders, and relatively small populations scattered across multiple islands. For criminal enterprises, the relatively low risks of detection of transnational and organised crime in this environment, along with its profitability, contribute to the growing attractiveness of the region as a potential crime hub. The perpetrators may assess opportunities for profit against the risks of detection, investigation, and prosecution by local, regional and international law enforcement agencies. In doing so, they weigh the perceived capabilities and limitations of such agencies and their likely willingness – or reluctance – to engage in complex and costly transnational investigations (Dandurand 2007, Williams and Godson 2002). Adding to these challenges, policing organisations in many PICTs are often under resourced (McLeod 2009). The complexity of transnational and organised crime makes it notoriously difficult to detect, monitor, investigate and respond effectively to the illegal activities involved even for well-resourced police organisations. In PICTs, the challenges are exacerbated by the vast geographic expanses of ocean and the limited resources available for patrolling it. For many PICTs, the legal systems are not well equipped to deal with the magnitude or types of crimes taking place within their jurisdictions (Schloenhardt 2009). Some crime classifications are yet to be included in local legislation, further limiting the extent to which they can be adequately addressed. Organisations thus encounter myriad challenges in their attempts to mount appropriate responses to new and emerging threats. Dialogue at the regional level has raised questions about the response capacity of security service providers – including customs, immigration, and police – to deal with current and emerging transnational and organised crime threats. This paper considers the nature of the threats, existing legislation, policing resources and Pacific specific approaches to capacity development. We conclude that, to be most effective, capacity development must be led by the PICTs and undertaken in light of a nuanced understanding of existing capacities and limitations within the region.