While the design and implementation of cascade reactions in organic chemistry and enzymatic biosynthesis flourished in the past decades, cascade reactions in polymerization remain an emerging concept with exciting opportunities. Cascade polymerization techniques can be used to generate polymers in which unique structures and functionalities are incorporated in the backbone of polymers, making them powerful tools to address the ever-increasing demand for new materials with improved functionality and sustainability. This Perspective highlights existing strategies for chain-growth cascade polymerizations following radical, ionic, nucleophilic, and transition metal catalysis mechanisms, with a focus on the design principle and reaction mechanism. Collectively, recent work illustrates the considerable potential and predicts future developments of chain-growth cascade polymerization, an active research field at the intersection of polymer science and organic chemistry.