Seven 35% solids, (83 : 17 in mol %), vinylidene chloride (VDC)–butyl methacrylate (BMA) copolymer latexes were prepared at 25°C using redox catalyst by batch and seeded semicontinuous emulsion copolymerization processes: one batch (G), one seeded batch (F), and five seeded semicontinuous polymerizations of five different monomer feed rates ranging from 0.27 (A) to 1.10 (E) wt %/min. All of the emulsion polymerizations gave stable latexes of almost 100% conversion with negligible coagulum and narrow particle size distributions. The kinetic studies of seeded semicontinuous polymerization A–E showed that the rates of polymerization (Rp) were controlled by the monomer addition rates (Ra), and polymerizations A–D (0.27–0.79 wt %/min) were under monomer-starved conditions; polymerization E (1.10 wt %/min) was in near-flooded condition. Significant differences were found in the physical and mechanical properties of the latex films, depending on the mode of monomer addition. Infrared spectroscopy, 13C solid-state NMR spectroscopy, X-ray diffraction, the Tg and Tm values by DSC, dynamic mechanical spectroscopy, and tensile strength measurement of the latex films post-heat-treated for 30 min at 70°C or aged for several months at room temperature demonstrated that batch polymerizations F and G gave copolymers of heterogeneous composition and a crystalline character. In contrast, semicontinuous polymerizations A–E gave copolymers of more uniform composition and an amorphous character.