Copepod species and major groups of zooplankton were identified from 513 samples taken at 20 stations on 5 transects in the coastal waters of the northwestern Gulf of Mexico. Monthly samples, using oblique tows and a Gulf V sampler (aproximately 200 um mesh size), were taken over a 3-year period from 1963-65. The bottom depths of the sampling stations ranged from 8 to 73 m. Temporal and spatial distributional patterns were examined in detail for major groups of zooplankton and common species of calanoid and cyclopoid copepods. The relationships between the densities of these groups and various physical and chemical factors were also examined.