Antimicrobial peptides (AMPs) are host-defense molecules produced by all living organisms, including bacteria, fungi, plants, invertebrates, and vertebrates. The peptides exhibit potent cytotoxic activity against all microbes, including bacteria, fungi, viruses, and parasites. There is now evidence in humans and other mammals that these peptides represent a key component of host defense at epithelial surfaces, the barrier between the external environment and the interior milieu, interacting with both symbionts and pathogens. Members of these large families also have activities far beyond being directly antimicrobial, including immunity, wound healing, fertility, and as ligands for numerous receptors leading to the induction of a variety of signaling pathways. Furthermore, significant research has been carried out to develop these naturally occurring peptides as therapeutic agents against microbial infections. The 2013 Gordon Conference on Antimicrobial Peptides will present the latest research on the biology and activities of AMPs with emphasis on their roles in host defense against all forms of microbial pathogens. The Conference will feature a wide range of topics, such as structure/function analysis, regulation of expression, mechanisms of action, microbial avoidance strategies, human disease associations and model systems, and the development of antimicrobial peptides and their mimetics as therapeutics. Invited speakers represent a diverse variety of scientific disciplines, including biochemistry, molecular genetics, microbiology, animal and plant biology, structural biology, medicine, innate immunity, signaling, and drug development. The Conference will bring together a collection of investigators who are at the forefront of their field, and will provide opportunities for junior scientists and graduate students to present their work in poster format and exchange ideas with leaders in the field. Some abstracts and poster presenters will be selected for short talks. The collegial atmosphere of this Conference, with programmed discussion sessions as well as opportunities for informal gatherings in the afternoons and evenings, provides an avenue for scientists from different disciplines to brainstorm and promotes cross-disciplinary collaborations in the various research areas represented.