In this article, the author discusses the role of window films in enhancing indoor air quality in schools. Historically, window film has been used to reduce temperatures in buildings prone to overheating. Too much solar energy entering through windows makes occupants uncomfortable and air conditioning more costly. Film has been a simple solution for a simple problem. But the environmental issues facing school buildings extend beyond overheating and energy conservation. Many measures intended to increase energy efficiency--such as "tightening" buildings to reduce air infiltration and outflow--have led to negative impacts on indoor environmental and air quality. Sick-building syndrome threatens building occupants and can result in costly lawsuits. Thus, school building designers must address issues such as under-ventilated and circulated air, moisture and mold growth, offgassing of furniture and building components, and how such conditions affect the productivity and well-being of students, faculty and staff.