Abstract: Curable acrylate ester compositions having as an accelerator for the polymerization a hydrazine derivative of the formula R.sup.1 --HN--NH--CO--R.sup.2 and as a co-accelerator, an acid having a pK.sub.a of less than about 6. The compositions may optionally be formulated as two-part compositions with the non-ester-containing part being applied as a primer. Typical of the monomers are the polyalkylene glycol dimethacrylates and the so-called urethane acrylates. Polymerization is preferably initiated by a peroxy compound such as cumene hydroperoxide, such a composition having anaerobic curing characteristics.