The size of schools and districts in which they are located has become a salient policy issue in recent years. While consolidation of school districts and expanding high school size were in vogue from the 1960s until recently, funding agencies are now sponsoring projects to reduce school size under the assumption that smaller schools will lead to higher academic achievement. There has been some scholarly work that focuses on the effects of size on achievement and recently, this literature has included district size and the competitive effects that size might generate on educational outcomes. In this paper, we focus explicitly on both district size and school size and look at a particular aspect of educational output. We argue that average daily attendance (ADA) is an output variable that is influenced by the enrollment in a school and the number of schools in a district. School attendance is critical to both achievement and dropout rates and is a directly measurable attribute of schooling. We use data from Texas schools and school districts to estimate size effects on this important policy variable.