While many studies have demonstrated the sensitivities of plants and of crop yield to a changing climate, a major challenge for the agricultural research community is to relate these findings to the broader societal concern with food security. This paper revies the direct effects of climate on both crop growth and yield and on plant pests and pathogens and the interacitons that may occur between crops, pests, and pathogens under changed climate. Finally, we consider the contribution that better understanding of the roles of pests and pathogens in crop production systems might make to enhanced food security. Evidence for the measured climate change on crops and their associated pests and pathogens is starting to be documented. Globally atmospheric [CO₂] has increased, and in northern latitudes mean temperature at many locations has increased by about 1.0-1.4°C with accompanying changes in pest and pathogen incidence and to farming practices. Many pests and pathogens exhibit considerable capacity for generating, recombining, and selecting fit combinations of variants in key pathogenicity, fitness, and aggressiveness traits that there is little doubt that any new opportunities resulting from climate change will be exploited by them. However, the interactions between crops and pests and pathogens are complex and poorly understood in the context of cliamte change. More mechanistic inclusion of pests and pathogen effects in crop models would lead to more realistic predictions of crop production on a regional scale and thereby assist in the development of more robust regional food security policies. ; Citation: Gregory, P. J. et al. (2009). 'Integrating pests and pathogens into the climate change/food security debate', Journal of Experimental Botany 60(10), 2827-2838. The definitive publisher-authenticated version is available online at: http://jxb.oxfordjournals.org/content/60/10/2827.full.pdf+html