The present invention concerns methods and compositions of use for treatment of Alzheimer's Disease (AD). In certain embodiments, the methods concern preparation of phage-display single chain antibody libraries and screening against amyloid-beta (A.beta.) protein or peptide. Anti-A.beta. antibodies are selected and sequenced. In certain embodiments, synthetic A.beta. binding peptides are designed and prepared, using portions of the anti-A.beta. antibody sequences. The antibodies and peptides are of use for treatment of AF or for treatment of individuals at risk of developing AD. Compositions comprising anti-A.beta. antibodies or A.beta. binding peptides are also disclosed.