A tailored nanoparticle modification approach for fibre reinforced polymers (FRP) is presented that allows exact analysis of the impact of a nanoparticle matrix modification in either 0°- or 90°-layers of cross-ply laminates on the mechanical properties and damage mechanisms. A modification of the 0°-layers unexpectedly increases the quasi-static tensile strength, although dominated by fibre properties. Positive crack stopping effects as well as negative effects, such as accelerated delamination growth, are discussed. The applicability of nanoparticle modified resin systems to improve the performance of FRP-laminates is sensitive to the loading case. For laminates only loaded in tension a modification appears to be advantageous, whereas in case of bending or compression loads the effect of nanoparticles is ambiguous and should be applied carefully.