On a clear day, from the height of an airplane circling over the Pampa Ingenio in Southern Peru, one may see the enigmatic ground drawings or geoglypha which have puzzled scientists since their discovery in the 1930s. Etched across the landscape near the Nazca River are lines and lifelike drawings depicting monkeys, birds, fish and spiders. The pre-Incaic Nazca peoples who made these geoglyphs created them by removing masses of surface stones to expose the lighter soil beneath. Various theories, some absurd, some plausible, have been formulated which seek to explain the meaning and purpose of the Nazca lines. A current theory is that the lines or geoglypha might have functioned like the ceques of Cuzco (from the quechua "ray") which organized into structured social, geographic and political units. It may also be that some of the lines were astronomically oriented and that they were related to water, agriculture and mountains. After several years (1976-1984) of investigation, Dr. Anthony F. Aveni and his team of interdisciplinary researchers consisting of Dr. Gary Urton (anthropologist) of Colgate University, Dr. C. L. N. Ruggles (astronomer) of the University of Leicester, Dr. Persis Clarkson (archaeologist) of Athabaska University, Dr. Helaine Silverman (archaeologist) of the University of Illinois and a group of investigators from the Remote Sensing Laboratory of the University of Minnesota have assembled their results here for the first time. These include a complete description and statistical analysis of the Nazca features, the surface archaeology of the pampa and the nearby ceremonial center of Cahuachi, and the possible relationship between the lines and pan-Andean systems of social organization. A critical assessment of previous theories advanced about the lines rounds out this collection of joint research papers.