The amyloid- β (A β) peptide is a key aggregate species in Alzheimer's disease. Although important aspects of A β peptide aggregation are understood, the initial stage of aggregation from monomer to oligomer is still not clear. One potential mediator of this early aggregation process is interactions of A β with anionic cell membranes. We used unconstrained and umbrella sampling molecular dynamics simulations to investigate interactions between the 42-amino acid A β peptide and model bilayers of zwitterionic dipalmitoylphosphatidylcholine (DPPC) lipids and anionic dioleoylphosphatidylserine (DOPS) lipids. Using these methods, we determined that A β is attracted to the surface of DPPC and DOPS bilayers over the small length scales used in these simulations. We also found supporting evidence that the charge on both the bilayer surface and the peptide affects the free energy of binding of the peptide to the bilayer surface and the distribution of the peptide on the bilayer surface. Our work demonstrates that interactions between the A β peptide and lipid bilayer promotes a peptide distribution on the bilayer surface that is prone to peptide-peptide interactions, which can influence the propensity of A β to aggregate into higher-order structures.