Laminar mixed convection in a two-dimensional shallow inclined lid-driven cavity is investigated numerically. The moving cavity lid at the top is isothermally hot and the bottom is isothermally cold while the two sidewalls are insulated. The cavity aspect ratio is taken as 10. The fluid medium consists of a mixture of pure water and copper nanoparticles with volumetric concentrations of 5% and 8%. The flow Richardson number is varied from 0.1 to 10, and the cavity inclination is varied from 0 deg to 30 deg. It is found that, at any specific nanoparticle concentration, the average Nusselt number increases mildly with cavity inclination for the forced convection dominated case (Ri = 0.1) while it increases much more rapidly with inclination for natural convection dominated case (Ri = 10). Also the average Nusselt number has significant increasing trend with increasing concentration of the nanoparticles.