Resins containing plant oil-based cross-linkers were studied with two reactive diluents: a styrene and an acrylated fatty acid methyl ester-based (AFAME) monomer. Acrylated epoxidized soybean oil and maleinated castor oil monoglyceride were bio-based cross-linkers used. The viscosity and mechanical properties of the resulting polymers were measured and analyzed. Both bio-based cross-linkers prepared using the modified AFAME as diluent had a fairly high viscosity, so blends of AFAME and styrene were needed to meet the viscosity requirements established by the composite industry (<1000 cP at room temperature). In addition, the glass transition temperature (T-g) and stiffness of bio-based cross-linker/AFAME polymers were significantly lower than the resin/styrene polymers. Ternary blends of maleinated castor oil monoglyceride with AFAME and styrene improved the mechanical properties to acceptable comparable values (storage modulus at 30 degrees C similar to 1200 MPa and T-g similar to 100 degrees C). The addition of 5 wt% of chemically modified lignin led to an improvement in the mechanical properties of the polymeric matrix but caused an increase in the viscosity. POLYM. ENG. SCI., 49:2384-2392, 2009. (C) 2009 Society of Plastics Engineers