Neutral methacrylate monomers undergo transesterification in methanol to produce multiple by-products under copper-catalyzed atom transfer radical polymerization (ATRP) conditions. The side-reactions occur for a range of hydrophilic methacrylates but some may be reduced by employing higher alcohols. This study demonstrates that care must be taken when using alcohol solvents for the synthesis of architecturally and compositionally pure methacrylate (co)polymers via copper-catalyzed conventional ATRP.