This study aimed to research the effectiveness of Group Guidance act of assistance using Assertive Training Techniques in increasing the assertive behavior of class X students of SMA Negeri 10 Pontianak. The method used in this study was quantitative in the form of a Pre-Experimental Design with a Pre-test "“ Post-test One Group Design research design. Total population of 34 students. Sampling by selecting students whose pre-test results were less than 66 so that in the end a sample of 10 students with a low level of assertive behavior was obtained. Based on the mean results of the pre-test before being given treatment of 61.3 and the post-test after being given treatment of 90.7. then obtained T count using the Paired Sample T-test, namely 9 with a value of Sig. (2 tailed) 0.00<0.05 which means that Hâ‚ is accepted and Hâ‚’ is rejected, thus there was a significant difference between the assertive behavior of students before and after being given Group Guidance act of assistance using the Assertive Training Technique. So it can be concluded that Group Guidance act of assistance with Assertive Training Techniques are effective in increasing the assertive behavior of class X students of SMA Negeri 10 Pontianak.
