The interactions of the antimicrobial peptide maculatin 1.1 (GLFGVLAKVAAHVVPAIAEHF-NH(2)) with model phospholipid membranes were studied by use of dual polarisation interferometry and neutron reflectometry and dimyristoylphosphatidylcholine (DMPC) and mixed DMPC-dimyristoylphosphatidylglycerol (DMPG)-supported lipid bilayers chosen to mimic eukaryotic and prokaryotic membranes, respectively. In DMPC bilayers concentration-dependent binding and increasing perturbation of bilayer order by maculatin were observed. By contrast, in mixed DMPC-DMPG bilayers, maculatin interacted more strongly and in a concentration-dependent manner with retention of bilayer lipid order and structure, consistent with pore formation. These results emphasise the importance of membrane charge in mediating antimicrobial peptide activity and emphasise the importance of using complementary methods of analysis in probing the mode of action of antimicrobial peptides.