This study used latent class analysis with data from the 2002/03 Head Start Impact Study to determine whether early childhood classrooms can be sorted into classroom quality groups based on their scores on multiple measures of quality, how many classroom quality groups could be identified, and what percentages of classrooms fall within each classroom quality group. Based on the 13 measures examined, Head Start and center-based early childhood classrooms could be grouped into three distinct classroom quality groups: good, fair, and poor. Classroom quality measures determined by independent observers distinguish classroom quality groups better than self-reported measures do. (author abstract)