The Indoor Environment Team estimates that modest improvements in the indoor environments where 89 million Americans work could prevent cases of respiratory infection, exacerbations of asthma, or allergies among 6-10 million workers annually. Improvements in these environments could also reduce frequently experienced building-related symptoms among 8-30 million workers. The potential economic benefits from reducing these adverse health outcomes are estimated at billions of dollars for workers and employers annually, including over $1 billion from reductions in costs of health care and over $6 billion from reductions in sickness absence and performance impairment. These estimates of health and economic benefits, based on the limited available data and reasonable assumptions, are inexact, but nonetheless indicate that the magnitude of benefits could be large. The team has identified three interrelated categories of high priority research needs: 1. Understanding the causes and prevention of building-related health effects; 2. Advancing the science and technology of indoor environments and buildings; and, 3. Identification and evaluation of strategies to reduce barriers and increase incentives for health-protective building practices.