Due to increasing resistance development, antimicrobial peptides (AMPs) are receiving increasing attention since these may provide rapid and broad-spectrum response to a host of pathogens. In addition, some of these peptides provide also strongly antiinflammatory responses, and are therefore promising in therapies of both acute and chronic inflammation. Critical for their antimicrobial action is the interaction between AMPs and bacteria membranes, where significant current efforts are directed to identifying peptides being potent antimicrobials, yet simultaneously displaying low toxicity. In inflammation, additional aspects are of importance, including interaction with lipopolysaccharide and other bacterial components. In our efforts to adress these and other challenges in the development of such peptides to practical therapeutics, our research addresses various aspects of interaction of AMPs with lipid membranes, bacteria, and cells. Focusing on endogenous peptides generated during normal microbial infections, we combine basic biophysical investigations on various aspects of AMP-membrane interactions with modern biotechnological tools for peptide design, and with biological experiments including bacteria, cells, and various animal models. Some recent examples of the work done in these contexts will be provided, aiming at synthesizing biophysical and biological aspects of these peptides.