This report describes the sample selection procedures used for a study funded by the EPA and conducted by the Research Triangle Institute in 1982 and 1983 to evaluate methodology for collecting data on personal exposure to carbon monoxide (CO). These data were collected in the metropolitan areas of Denver, Colorado and Washington, D.C., using personal exposure monitors (PEMs) and activity diaries. This involved telephone screening of households and selection of household respondents for personal exposure monitoring in the metropolitan areas in and around Denver, Colorado and Washington, D.C. Data on CO breath levels were also collected in Washington, D.C. (PEDCo Environmental conducted the field work in Denver.) The target population in both cities consisted of the non-institutionalized, non-smoking adults (ages 18 to 70) of these metropolitan areas. Based on the experience gained during the study, the methodology developed, with some modifications, may be used effectively in other areas of the country for collecting PEM data. These modifications should make the methodology more cost effective, improve the response rate, and lead to more accurate activity information.