Inverse emulsion copolymerization of (2-methacryloyloxyethyl) trimethyl ammonium chloride with acrylamide initiated with potassium persulfate has been studied dilatometrically. Aqueous monomer solutions were emulsified in kerosene with a blend of two surfactants (Span80 and OP10). The gel effect is evident from the increase of the molecular weight with conversion and also from the percentage of conversion versus time curves. Monomer reactivity ratios have been derived as r(AM) = 0.38 and r(DMC) = 1.69 at pH 6.8. The effects of initiator concentration, concentration, and composition of the monomer, emulsifier concentration, etc., on the polymerization rate and intrinsic viscosity of polymer have been examined. The rate of polymerization (R-p) can be represented by R-p proportional to I-0.52[M](1.50)[E](0.38). The overall activation energy for the rate of polymerization is 66.0 kJ mol (40-65 degrees C). Based on these experimental results, some aspects of the polymerization mechanism are discussed.