Curable adhesive compositions comprising vi. a curable epoxy resin vii. an amine curing agent, viii. a polymeric toughening agent, ix. a filler and x. a phosphoric acid ester according to the formula as an adhesion promoter, wherein R represents an aliphatic or aromatic residue that contains one or more carboxylic acid ester units and/or one or more urethane units and that further contains at least one ether group and n represents an integer of 1 or 2, methods of making them, bonded articles and methods for bonding.