The purposes of this research were to compare the students’ English grammatical knowledge before and after learning through Team Game Tournament activity, and to study the students’ English speaking ability and social skills after learning through Team Game Tournament activity. The target group was 38 MathayomSuksa 1/3 students taking the Fundamental English (Eng. 21101) in the first semester of academic year 2013 at SanpatongWittayakom School, Sanpatong District, Chiang Mai. The experimental instrumets were 7 lesson plans using Team Game Tournament activity. The data collecting instruments were the grammar test, English speaking ability assessment, and social skills assessment. The target group learnt through Team Game Tournament activity for 7 weeks. The grammar test was administered before and after the experiment. English speaking ability and social skills were assessed after learning through Team Game Tournament activity in every lesson plan. The data obtained were analyzed for the mean, standard deviation, and percentage. The findings were as follows.