The initiation system comprises (1) at least one silylated initiator and (2) at least one alkaline metal alcoholate as ligand. The silylated initiator may be monofunctional and selected in particular from among the compounds of Formula (I) or difunctional and selected in particular from among the compounds of Formula (II): wherein R1, R2, R3 each independently represent a C1-C8alkyl radical, linear or branched; R4 is a linear or branched C1-C8alkylene radical; M is an alkaline metal or alkaline earth metal (valence q of 1 or 2); R5 and R6 each independently represent an alkyl radical, linear or branched, at C1-C8; R7, R8 each independently represent a C1-C8alkylene radical, linear or branched; M′ is an alkaline metal. Application is to the preparation of (meth)acrylic (co)polymers.