Abstract: The invention herein comprises antibodies that bind to amyloid beta-derived diffusible ligands (ADDLs). ADDLs comprise amyloid &bgr; protein assembled into soluble, globular, non-fibrillar, oligomeric structures capable of activating specific cellular processes. The invention also comprises methods of using ADDL-specific antibodies for assaying the formation, presence, receptor protein binding and cellular activity of ADDLs, as well as using such antibodies to detect compounds that block the formation or activity of ADDLs, and methods of identifying such compounds. The invention further provides methods of using ADDL-specific antibodies in modulating ADDL formation and/or activity, inter alia in the treatment of learning and/or memory disorders.