The aim of this study was to evaluate the ability of dental students at different levels of education (Basic, Preclinic, and Clinic groups) to assess the level of gingival health status by using the Development of Ability to Assess Gingival Status (DAAGS) computer software program designed according to the Oral Rating Index (ORI) criteria. Two hundred and thirteen dental students at three levels of dental education voluntarily participated in three DAAGS tests in which they judged twenty-four photos. The three groups were first- and second-year dental students (Basic), third- and fourth-year dental students who had not yet participated in the clinical periodontology course (Preclinic), and fifth-year dental students who had completed the clinical periodontology course (Clinic). A gold standard of each photo was shown after completing Test 1, and then Test 2 was conducted immediately. Two weeks later, the third test was performed. Analyses of differences among the groups and between the tests for each groups were carried out by using Kruskal-Wallis and Wilcoxon Sign Rank tests, respectively. Students were asked to evaluate the DAAGS by written survey. Most of the students had a positive opinion. There were significant differences among the groups for correct and irrelevant answers and overall ability (p<0.01) improvement between Test 1 and Test 2. This improvement was greater than Preclinic students and almost equal to Clinic students. The findings from this study indicate that the DAAGS software can serve as a useful instructional tool for education.