The miscibility behavior of poly(2,2-dichloroethyl methacrylate) (PDCEMA) and poly(2,2,2-trichloroethyl methacrylate) (PTCEMA) with various polymethacrylates was examined using differential scanning calorimetry. PDCEMA and PTCEMA are both miscible with poly(methyl methacrylate), poly-(ethyl methacrylate), poly(n-propyl methacrylate) (PnPMA), poly(isopropyl methacrylate) (PiPMA), poly-(tetrahydrofurfuryl methacrylate), and poly(cyclohexyl methacrylate) but immiscible with poly(n-hexyl methacrylate). They differ in those cases involving poly(n-butyl methacrylate) (PnBMA), poly(n-amyl methacrylate) (PnAMA), and poly(isoamyl methacrylate) (PiAMA). PDCEMA, but not PTCEMA, is miscible with PnBMA and PiAMA. PDCEMA has a limited miscibility with PnAMA, but PTCEMA is immiscible with PnAMA. Miscible blends of PDCEMA with PnPMA, PiPMA, PnBMA, and PiAMA showed lower critical solution temperature behavior. PDCEMA shows a wider range of miscibility with polymethacrylates than PTCEMA and other chlorine-containing polymethacrylates such as poly(chloromethyl methacrylate), poly(1-chloroethyl methacrylate), poly(2-chloroethyl methacrylate), and poly(3-chloropropyl methacrylate). The good miscibility of PDCEMA appears to be correlated to the acidic hydrogen in the pendant -CHCl2 group.