Under the 2001 reauthorization of the Elementary and Secondary Education Act of 1965, states developed their own assessments and set their own proficiency standards to measure student achievement. This has resulted in a great deal of variation among the states, both in their proficiency standards and in their student assessments (NCES 2008-475). This variation has created a challenge in understanding the ability levels of students across the United States because there is no means to compare the proficiency levels established by one state against the others directly. To address this need, the National Center for Education Statistics (NCES) has published periodic reports for the past 10 years in which the National Assessment of Educational Progress (NAEP) is used as a common metric for examining the proficiency standards set by states in reading and mathematics in grades 4 and 8. This report, the fifth in the series, presents the results of applying a methodology for mapping state proficiency standards onto the NAEP scales by using state public school data for the 2012-13 school year and the 2013 NAEP assessments in reading and mathematics for grades 4 and 8. The report also includes analyses of the results using the 2011 NAEP and state assessment data and revised estimates for 2009 reported in NCES 2011-458. The key finding is that the variation among state achievement standards continues to be wide. The following are appended: (1) 2011 Mapping Results; (2) Revised 2009 Mapping Results; (3) Supporting Tables; and (4) Similarity of State Assessments and NAEP.