The purpose of the present study was to compare the understanding of conventional time concepts by urban preschool children reared in poverty with that of their peers not raised in poverty. The questionnaire used in this study was based on the original work of Ames. Thirty-six children ranging in age from three to five years of age participated in the study. Twelve attended a Head Start program for homeless children, 12 lived in low-income housing and attended a neighborhood Head Start program, and 12 attended one of three university daycare centers. Each child was interviewed using a questionnaire containing age, calendar, clock, experiential and conceptual time-related questions. The results of this study revealed that homeless children and children living in poverty who attended Head Start programs possessed less conventional time knowledge than their peers who attended university daycare centers, as well as those children who participated in the original Ames study. These results have important implications for educational practices. (Contains 3 tables.)