This case study illustrates the contemporary archaeological field of ethnobotany, and explores the interrelationships between the prehistoric residents of a small valley in coastal Ecuador and the dry tropical forest habitat in which they lived. The work has three related objectives: 1. it is an ethnobotany - a work that explores how, through the medium of culture, people shape and are shaped by the environment in which they live, 2. it is a work that synthesizes results of some 10 years of research done by Pearsall during the Jama Archaeological-Paleoethnobotanical project, and 3. it is a work that provides Pearsall with the opportunity to illustrate paleoethnobotanical research methods, an important component of contemporary interdisciplinary archaeology. Pearsall took as her subject the 3,600-year-old archaeological record of the Jama River valley in northern Manabi, Ecuador, and she determined what plants people selected for food, fuel, building materials, and ritual; evaluated the impact of agricultural activities on the tropical forest environment; and examined the response of populations to volcanic ash fall disasters. Broken into four parts, this case study starts with an introduction to the field of ethnobotany, then goes on to describe Pearsall's experiences doing field work in the Jama River Valley and the results of her research, and concludes with an illustration of how ethnobotany fits into and contributes to archaeology.