Several states had an assessment that they considered to be an alternate assessment based on modified academic achievement standards (AA-MAS) in place, or in development, when the April 2007 federal regulations on modified achievement standards were finalized. This article uses publicly available information collected by the National Center on Educational Outcomes to analyze changes in states' AA-MAS between 2007 and 2008. The article compares across the 2 years the number of states that had an assessment they considered to be an AA-MAS, states' participation guidelines, and the characteristics of these assessments. We also provide information about the number of students who participated in this assessment option during the 2006-07 school year. In 2007, six states (Kansas, Louisiana, Maryland, North Carolina, North Dakota, Oklahoma) either had or were in the process of developing an assessment they considered to be an AA-MAS. In 2008, California, Connecticut, and Texas also offered this assessment option. Six of the nine states that have been early implementers of the AA-MAS were states that had offered an out-of-level testing option until federal policies required that option to be phased out. Most states had fewer items on their AA-MAS than on their regular assessment. States that had participation guidelines for the AA-MAS in 2007 developed them prior to finalization of the federal regulations, and some changes between 2007 and 2008 in states' participation guidelines appear to have been made to better align the guidelines with the regulations. The characteristics of the assessments states consider to be AA-MASs are changing rapidly and will probably continue to change rapidly over the next few years as more is learned about the advantages and limitations of this assessment. (Contains 5 tables and 4 footnotes.)