• Previous studies have suggested that poor, urban parents are often unable to identify the presence of fever by use of a mercury glass thermometer. We investigated whether 145 mothers whose children received care in an urban hospital ambulatory care center could accurately read a thermometer. If they could not, their ability to identify zones of temperature, either by use of colors or numbers, was assessed. Although 57.9% of parents owned a mercury glass thermometer, only 9.7% could accurately read three thermometers presented to them. When those parents who were unable to accurately read were asked to identify the zones of temperature within which the mercury fell, 87.0% could successfully identify number zones; 78.6% could correctly identify color zones. Teaching the zone-reading techniques required only 15 to 30 seconds. We conclude that for parents unable to read a thermometer by conventional means, the use of color zones or number zones is a technique that is easily taught and reliably carried out.