A series of nanocomposites were prepared from graphene platelets (GPL) and a flexible biobased epoxy thermoset matrix derived from cashew nut shell liquid. The loading of GPL in the biobased thermoset matrix ranged from 0.1 to 0.8 wt % and resulted in increased tensile strength and Young's modulus (17 to 33 MPa and 474 to 1700 MPa, respectively). Increases in mode I fracture toughness for K-IC and G(IC) ranged from 0.6 to 1.9 MPa.m(1/2) and 906 to 1734 J/m(2), respectively. Furthermore, dynamic mechanical analysis revealed that GPL incorporation resulted in increases in the alpha-transition temperature (peak of the loss modulus) from 27 to 50 degrees C and increases the storage modulus from 1000 to 2000 MPa. Also, introduction of GPL increased the onset of degradation (T-d3%) for the biobased thermoset matrix by 30 degrees C. Results of this work demonstrate that incorporation of graphene platelets enhances all measured physical and thermal properties of the cashew nut shell derived epoxy resin and enables higher performance applications.