In the title compound, C(16)H(13)NO(2), the 2,3-dimethyl-phenyl group and the 1H-isoindole-1,3(2H)-dione group are essentially planar, with r.m.s. deviations of 0.006 and 0.013 Å, respectively, and are oriented at an angle of 78.19 (3)° with respect to each other. In the crystal, weak C-H⋯O inter-actions link the mol-ecules, forming a zigzag chain parallel to the b axis. Futhermore, C-H⋯π inter-actions are present between the C-H group of isoindole and the 2,3-dimethyl-phenyl benzene ring. The H atoms of the ortho-methyl group are statistically disordered over two positions. Such disorder might be related to the antagonism between intra-molecular steric repulsions and inter-molecular C-H⋯O inter-actions.