Three new harpacticoid copepods from the Santa Maria Basin off the south-central Californian coast are described: Zosime pacifica n. sp., Cletodes macrura n. sp. Cletodes tuberculatus n. sp. The three species are the most dominant harpacticoids found during a sampling program studying the possible effects of oil and gas developments in this area. The description of the copepodids of each species is included and a key to the species of the genus Cletodus is given.