Editors' Summary: Over the past couple of decades, as awareness of hazardous waste contamination has grown, the exposure of children and adults to hazardous wastes via ingestion of contaminated soil has emerged as a dominant concern in risk assessment. This Dialogue summarizes the results and implications of a multiproject research endeavor to estimate soil ingestion in children and adults. The authors begin by explaining how soil ingestion studies are conducted. They also discuss how to differentiate among soil ingestion studies of different quality. They then summarize how to use soil ingestion studies to glean insights into the more critical aspects of soil ingestion that relate to risk, such as how to differentiate dust ingestion from soil ingestion, how to estimate soil ingestion on different days, and how to average ingestion over multiple days. The authors note that while researchers have performed several studies on soil ingestion by children, significant gaps remain in the knowledge on this subject. Studies evaluating differences in soil ingestion by comparing regions of the country, by comparing urban and rural populations, and by comparing seasons of the year remain to be performed. The authors further point out that studies on soil ingestion by adults are limited and that considerable uncertainty still exists in this area. Thus, while this project has resulted in significant gains in risk assessment, there are more questions to be resolved.