We studied ostracod assemblages from an 1800-year sediment record from a Jamaican lake to evaluate causes of change and to test a previous interpretation from a Late Pleistocene record, which suggested that lake-level change was the main control. We found that, rather than being a simple response to changing lake level, ostracod assemblage changes are a complex response to a range of factors. Our findings may have relevance to the interpretation of ostracod assemblages in other similar lakes.