The 9th killer cell immunoglobulin-like receptor (KIR) workshop was held in Winchester, United Kingdom late in the summer of 2015. The extraordinary diversity of KIR and its functional consequences were key themes throughout the meeting. Novel sequencing technologies and new bioinformatics techniques continue to increase our understanding of the genetic diversity and evolution of the KIR; whilst a deeper understanding of KIR functions, including their specificity for MHC and its peptide ligands, are generating more refined models of their role in disease. Limited to 100 delegates from around the world, this intimate workshop facilitated vigorous discussion, generating new ideas for research in this ever-expanding field.