Benzoxazine monomers comprising at least one pendant group are described. (Co)Polymers comprising at least one benzoxazine monomer having at least one pendant group are also described. In a preferred embodiment, the pendant group is located in a side chain of the benzoxazine monomer or polymer. Methods for preparing the benzoxazine monomers and polymers are described. Compositions comprising the benzoxazine monomers and polymers have numerous uses including optical materials, and in electronic materials as electrically insulating materials, and as fireproof materials.