The synthesis of the title compound, C(21)H(18)N(2)OS, involves the reaction of 3-methyl-benzoyl chloride with potassium thio-cyanate in dry acetone followed by condensation of the 3-methyl-benzoyl isothio-cyanate with diphenyl-amine. The carbonyl [C-O = 1.215 (2) Å] and thio-carbonyl [C-S = 1.6721 (17) Å] distances indicate that these correspond to double bonds. The short C-N bonds at the center of the mol-ecule reveal the effects of resonance in this part of the mol-ecule. The conformation of the mol-ecule with respect to the thio-carbonyl and carbonyl groups is twisted. The 3-methyl-phenyl and two phenyl rings are also twisted, with dihedral angles of 75.67 (9) and 14.91 (9)°. The phenyl rings are rotated out of the mean plane of the N-C-S-N atoms by 66.87 (8) and 78.40 (9)°. Pairs of mol-ecules are linked into centrosymmetric dimers via inter-molecular N-H⋯S inter-actions and a C-H⋯O link also occurs. The dimers are stacked along the a axis.