Alternate assessments based on alternate achievement standards (AA-AAS) are designed to measure the academic achievement of students with the most significant cognitive disabilities (SWSCDs). AA-AAS present unique measurement challenges because of the inherent need for individualization in item presentation and response, combined with expectations for rigorous levels of standardization. Additional measurement challenges are presented as states move toward implementation of growth models for accountability. This brief addresses some decisions that states face as growth models with AA-AAS are implemented.