Quantitative structural images of peptides in oriented arrays of fluid lipid bilayers are necessary for interpreting thermodynamic measurements of peptide-bilayer energetics in molecular terms. Lamellar x-ray and neutron diffraction provide a starting point for obtaining structural images. But the high thermal motion of fluid bilayers limits “structures” to so-called bilayer profiles, representing a time-averaged projection of the unit-cell contents onto an axis normal to the bilayer plane. Specific deuteration of lipid structural groups combined with neutron diffraction difference methods allow these profiles to be decomposed into a collection of groups (phosphates, carbonyls, etc.) representing transbilayer probability distribution functions. The power of this method has been extended through the inclusion of x-ray data and a joint-refinement protocol. We have developed an x-ray method, referred to as absolute-scale refinement, that permits the determination of the disposition of peptides in fluid bilayers. These various approaches can used in concert as a powerful tool for gaining structural information. But that information is still only one-dimensional. We are now developing methods for obtaining experimentally validated three-dimensional structures by combining the diffraction methods with molecular dynamics simulations. In essence, our goal is to convert 1-D experimental data into 3-D images. Importantly, these images will be dynamic, which will permit the ensembles of peptide-lipid structures to be explored in detail. An essential issue, however, is the validation of MD simulations using diffraction data. A method of accomplishing this objective will be described. Research supported in part by grants from the National Institute of General Medical Sciences (GM46283 and GM68002) and the National Center for Research Resources (RR14812).