Time series of phytoplankton pigment concentration along coastal and oceanic transects in the eastern tropical Pacific Ocean were derived from coastal zone color scanner monthly composite data for November 1978 through June 1986. Seasonal and interannual variability made up about half the total variance of the time series. Seasonal cycles typically consisted of a spring minimum and fall maximum, although many local variations were observed. Interannual variability was as great as seasonal variability and was dominated by the 1982--1983 El Ni¿o event. The decline in pigment concentration during 1983 was less to the west of the Galapagos than to the east and along the Central American coast. Physical forcing of pigment variability was investigated by testing correlations between pigment concentration and wind variables associated with upwelling and mixing. Seasonal cycles and some interannual changes in pigment concentration were correlated with local wind-driven processes that cause variation in primary productivity. Correlations between pigments and local winds in oceanic transects were different at seasonal and interannual scales, implying remote forcing at the interannual timescale.