This study evaluated the effect of the combi- nation of two dimethacrylate-based monomers [bisphenol A diglycidyl dimethacrylate (BisGMA) or bisphenol A ethoxylated dimethacrylate (BisEMA)] with diluents either derived from ethylene glycol dimethacrylate (ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol di- methacrylate) or 1,10-decanediol dimethacrylate (D3MA) on network characteristics and mechanical properties of neat resin and composite materials. The degree of con- version, maximum rate of polymerization and water sorp- tion/solubility of unfilled resins and the flexural strength and microhardness of composites (after 24 h storage in water and 3 months storage in a 75 vol% ethanol aqueous solution) were evaluated. Data were analyzed with two- way ANOVA and Tukey’s test (a = 0.05). The higher conversion and lower water sorption presented by BisEMA co-polymers resulted in greater resistance to degradation in ethanol compared with BisGMA-based materials. In gen- eral, conversion and mechanical properties were optimized with the use of long-chain dimethacrylate derivatives of ethylene glycol. D3MA rendered more hydrophobic mate- rials, but with relatively low conversion and mechanical properties.