The set of semicollisional layer equations derived by Fitzpatrick [Phys. Fluids B 1, 2381 (1989)] is used to investigate the effect of trapped particles on the linear stability of long wavelength resistive modes in a large-aspect-ratio tokamak. At 0( 1) shear, destabilization by trapped particles is found to significantly modify previous cylindrical results for the drift-tearing mode. At low shear, a fairly weak trapped particle-driven interchange (g mode) instability is found, in addition to the usual drift-tearing mode instability, which, in this limit, is virtually unaffected by trapped particles.
