We have performed an experimental study of meta- and para-xylene isomers, C6H4(CH3)(2), adsorbed on Pd(111). Using scanning tunneling microscopy we imaged the characteristic surface structures and investigated the molecular ordering for meta- and para-xylene. A triangular shape characterized the meta-xylene, and the para-xylene showed a distinctive diamond shape. Both isomers showed some propensity to order and a correlation between azimuthal orientation and the close-packed directions of the metal.