Distributional patterns of optical and particulate properties at oceanic fronts follow general patterns. These patterns are examined by means of three examples: the front associated with the Columbia River plume in winter, the upwelling front off the Oregon coast during the summer and the front in the eastern equatorial Pacific. It is shown that the optical and particulate matter distributions at oceanic fronts are the result of three major processes: (1) advection of inorganic matter into the frontal zone, (2) advection of biological materials into the front, and (3) generation of particulate matter by biological processes in the front itself.