Two-component semi- and full interpenetrating polymer networks (IPNs) of soybean-oil-based uralkyd resin (UA) and polyethyl methacrylate (PEMA) were synthesized by the sequential technique. The elastomers obtained were characterized by mechanical properties such as tensile strength, elongation, and hardness (Shore A). The apparent densities of these samples were determined and compared. Glass-transition studies were carried out using differential scanning calorimetry. The thermal characterization of the elastomers was undertaken with the aid of thermogravimetric analysis. Phase morphology was studied by scanning electron microscopy. The effect of the compositional variation on the aforementioned properties was examined. The maximum elongation for both the semi- and full IPNs was observed at 60% UA and 40% PEMA. Glass-transition studies revealed that there was a phase separation in the semi-IPNs as two T(g)s were obtained, whereas the full IPNs showed one T-g, indicating a single phase transition.