We demonstrate one- and two-dimensional transverse laser cooling and magneto-optical trapping of the polar molecule yttrium (II) oxide (YO). In a 1-D MOT, we characterize the magneto-optical trapping force and decrease the transverse temperature by an order of magnitude, from 25 mK to 2 mK, limited by interaction time. In a 2-D MOT, we enhance the intensity of the YO beam, while reducing the transverse temperature by more than a factor of two in both transverse directions.  We also present work toward demonstration of a 3-D MOT for polar molecules.