Pennsylvania System of School Assessment (PSSA) data from one rural school system covering four groups of children for a consecutive three year period was used to study the impact of transient students entering the school system. The analysis compared native children (those on roll since the first year) with transient children added to or deleted from the enrollment base of the district during 2006, 2007, 2008 academic years when the PSSA exam was administered. Significant differences favoring the achievement of native children were noted over the years of the study. A policy recommendation regarding data used for making Adequate Yearly Progress (AYP) is also presented in this paper. (Contains 5 endnotes and 4 tables.)