The total light scattering coefficient, the volume scattering function at 45°, and the suspended particle size distribution have been determined at the surface, at the depth of maximum turbidity, and at 100 meters at several stations in the eastern equatorial Pacific. The total scattering coefficient and volume scattering function were also measured at several other depths. Total light scattering was measured in situ with a b meter, the volume scattering function was measured in the ship's laboratory with a Brice-Phoenix light scattering photometer, and particle size distributions were determined in the ship's laboratory with a Coulter Counter. The total scattering coefficient is directly proportional to the volume scattering function at 45°. The total number of observed particles, total particulate cross section, and total particulate volume per cubic centimeter of sea water were computed from the measured particle size distributions. Both the total scattering coefficient and the 45° volume scattering function are roughly proportional to these properties of the suspended particles. A significant fraction of the light scattering is believed to be due to particles smaller than 1 μ, which were not measurable by the Coulter Counter.