High-solid-content (> 60 wt %) lattices of styrene (St), butyl acrylate (BA), methacrylic acid (MMA), and N-hydroxymethacrylic amide (NMA) were prepared through semicontinuous emulsion polymerization. In order to obtain high-solid-content lattices with low viscosity, the intermediate emulsion (IE) of the two-stage pathway had to have viscosity kept low, and so the amount of surfactant for the second stage was about 5-6 wt %. The relationships between IE viscosity and coagulum formation and between surfactant concentration and viscosity are discussed in this article. Particle size and particle size distribution (PSD) were investigated and are also discussed. Lattices through the two-stage pathway were found to have a bimodal PSD and good mechanical and chemical stability. However, lattices through the one-stage pathway had a narrow PSD and low mechanical and chemical stability.