Child-staff ratios are an important quality indicator. They are often collected by observing one randomly selected classroom several times during a 2-h period on a single day. However, it is unclear whether these measures represent the ratios that children actually experience during most of their time in care. This study compared ratio data collected from a single classroom during a 2-h period on a single day with data collected from multiple classrooms in the same center during 8-h periods over 10 days. Analysis of data from 77 child care centers found moderate correlations between the two measurement methods. Ratios measured during a 2-h period from a single classroom on a single day tended to underpredict ratios measured from multiple classrooms and multiple days. Results suggest that the representativeness of ratio measurements can be improved by lengthening the observation period and especially by measuring ratios in multiple classrooms.