Pacific island countries are among the most vulnerable in the world to the impacts of climate change, including the many and varied effects on human health. The vast majority of these health impacts are expected to be negative and the burden of climate change-attributable ill-health will be maldistributed, with the greatest suffering likely to be experienced by the poor. The objectives of the research described in this thesis were: a) To critically appraise various methods of assessing climate change and health vulnerabilities in Pacific island countries; b) To establish the key climate-sensitive health risks in each country; and c) To develop an evidence base for health systems adaptation to climate change in the Pacific region. Thirteen countries participated in this regional climate change and health vulnerability assessment and adaptation planning project between 2011 and 2013: Cook Islands, Federated States of Micronesia, Fiji, Kiribati, Marshall Islands, Nauru, Niue, Palau, Samoa, Solomon Islands, Tonga, Tuvalu and Vanuatu. This project, supported by the World Health Organization South Pacific office, employed a range of quantitative and qualitative techniques in the assessment and stratification of climate change and health risks for each country and the development of regional and country-specific adaptation strategies. The thesis presents the results of these analyses and describes in detail the predominant risks to health posed by climate change in the Pacific. These include: injuries and trauma; compromised safety and security of water and food (leading to malnutrition and gastrointestinal infections); vector-borne diseases; heat-related illnesses; zoonoses; respiratory ailments; psychological and emotional ill-health; increasing morbidity and mortality from non-communicable diseases; population pressures; and increased strain and pressure on health systems in these small island developing states. Correspondingly, the adaptation themes common across the region relate to improving the safety and security of food supplies and water, sanitation and hygiene facilities; enhancing infectious disease surveillance and response capabilities; building resilience within health systems and of health infrastructure; and increasing the accuracy and efficiency of communication and collaboration between the health sector and other agencies. The results of these assessments have been compiled into national climate change and health adaptation plans for each country, and synthesised in a World Health Organization report published in late 2015. The thesis summarises the main categories of adaptation strategies planned around the region and the health systems and policy landscape within which adaptation is taking place. In doing so, the thesis combines overviews of the vulnerabilities and adaptation plans from a regional perspective, along with examples of specific countries, including Federated States of Micronesia, Fiji, Kiribati and Vanuatu. The overall aim of this work is to enhance the ability of individuals, communities and health systems in the region to withstand the pressures and hazards posed by climate change, by providing a body of scientific evidence and a basis for sound policies aimed at protecting the health of Pacific Island people. It is clear that this will necessarily involve substantial support from wealthier countries - the messages are increasingly clear; the audience is global; and the timing is urgent.