Out-of-school suspension is defined as temporarily excluding a student from school and school related activities. High suspension rate may reflect poor education quality and unsupportive academic environment. Differential suspension based on a student's characteristics, such as race and social economic status is of great concerns, and efforts need to be made to eliminate the differences. This preliminary analysis focuses on investigating the effects of race, rate of economic disadvantage, and grade levels on suspension rates over a 5-year period. Preliminary results showed that suspension rates, as well as corresponding rates of racial and economic disproportionality were relatively stable over 5-year period. Logistic regression and mixed-effects model were used to explore the relationship between suspension and other variables.