This study aimed to examine the effectiveness of the anger control program for elementary schoolers. Initially, the anger control program targeting elementary schoolers was developed. This program was based on cognitive therapy but added some other therapeutic components, such as art therapy, socio-drama, and communication skills training. Then, the effectiveness of this program was tested. A total of 16 elementary students who received high (Anger Expression Group; AE group) and low scores (Anger Suppression Group; AS group) on the Children's Inventory of Anger (CIA: Finch, Saylor, & Nelson, 1983) participated. The anger control program developed was administered to both the AE and AS groups, and Total CIA scores and 4 scale scores of the CIA (Frustration, Physical Attacks, Peer Relationship, and Authority Relationship) were assessed at pre- and post-treatment. The results showed that in both groups, general levels of anger significantly reduced after the treatment. For specific dimensions of anger, the AE group reported significantly reduced levels in Peer Relationship and Authority Relationship after the treatment while the AS group reported significantly reduced levels of Physical Attacks after the treatment. Differential treatment effects of the program on the AE and AS groups were noted and possible reasons to cause these results were speculated.