This study explores the use of a mapping technique to test the invariance of proficiency standards over time for state performance tests. First, the state proficiency standards are mapped onto the National Assessment of Educational Progress (NAEP) scale. Then, rather than looking at whether there is a deviation in proficiency standards directly, the invariance of their NAEP equivalents is tested over time. The basis of the mapping technique is an enhanced method that was originally designed for comparing performance standards for public school students set by different states when the state tests are comparable. This approach can also be used to detect score inflation over time for state tests.