This is a tricky question, because ESGI is a program to which you can add your own assessments, collect data, and report it. Essentially, ESGI is not a curriculum, it is a platform for administering assessments, so it is only as reliable as the tests you use with it. For the tests that we have pre-loaded, all are basic tests that all kindergarten teachers give, such as letter recognition, number recognition, sounds, and sight words. These tests follow the research that Marie Clay did in her book, "An Observation Survey," and the sight words on The Fry Word List. The Friends of ESGI tests are based on experienced people in the field. You can see more information about each of them here.