The tropical eastern Pacific region has historically been characterized as devoid of coral reefs. The physical conditions of the region are apparently not conducive to reef growth: low temperatures, low salinity, and high nutrient loads. But recent work has demonstrated persistent coral growth in some locations at relatively high accretion rates, dating at least 5600 y before present. Coral reefs of the eastern Pacific are typically small (a few hectares), with discontinuous distribution and low species diversity. On a global scale, the eastern Pacific reefs may be considered minimum examples of coral reefs, as they have developed in possibly one of the most restrictive environments in the history of coral reefs. Disturbances are frequent, bioerosion intense, and recovery seems to be extremely slow. There is a general paucity of fossil corals and reefs on the American Pacific coast, probably due to the low preservation potential. In this review, distinct characteristics of the eastern Pacific and its coral reefs are highlighted. These factors make the region one of the smallest natural marine laboratories to study coral community structure and function on a regional level. The eastern Pacific is not only a testing ground for biological theory, but it is also a laboratory for paleoclimatic and oceanographic reconstruction.