"Safe, Healthy and Ready to Succeed: Arizona School Readiness Key Performance Indicators" presents a set of baseline measurements that gauge how well a statewide system of school readiness supports is addressing issues that affect Arizona children's readiness for school. The Key Performance Indicators (KPIs) measure the system, rather than the readiness of the individual child. Over 140 possible indicators were reviewed for inclusion. Only those indicators that are reliably available through health and welfare agencies, federal or national sources; that are currently collected and likely to continue to be collected so that progress can be measured over time; that correlate to conditions affecting children's readiness for school; and that represent conditions which a statewide system of supports can reasonably hope to affect were retained. The Key Performance Indicators (KPIs) include measures of several domains affecting children's readiness for school including child health and access to health care, family supports and conditions, access to high-quality early childhood education environments, and factors such as teacher education that affect program quality. Additionally, broad social and economic factors that pertain to school readiness in Arizona (such as poverty, migration, and English language proficiency) are reviewed. Arizona's KPIs provide a resource to other States in that they represent a set of measurements that can be modified to fit the conditions affecting school readiness in other localities. (Contains 119 endnotes.) [This report was produced by the State School Readiness Board, Governor's Office for Children, Youth and Families, Phoenix, Arizona.]