The stratigraphic, seddimentary pigment, loss—on—ignition, pollen, and radiocarbon data of a sedimentary record from Anangucocha, in the Ecuadorian Amazon, define three environmental episodes during the last 3100 yr. A swamp episode (<3100—1300 BP) was followed by regional flooding (1300—800 BP) and an open lake period (since 800 BP). Pollen data show that a Mauritia palm forest occupied the early blackwater swamp and was replaced by a riparian community dominated by Cecropia during the flooding episode. The pollen of Urticaceae—Moraceae taxa, especially Urtica, has increased in abundance since the flood. Past flooding was an important disturbance agent, which influenced the history of the plant community around Anangucocha. In the Amazon forest, such episodic flooding may be an important type of disturbance that promotes and maintains high species diversity. The Anangucocha record indicates that Amazonia experienced climatic fluctuation during the late Holocene.