Berdasarkan pengamatan yang dilakukan di kelas IX SMP ABC, ditemukan sebuah masalah dalam kegiatan belajar mengajar di kelas yaitu siswa belum menunjukkan keaktifan dalam mengikuti pembelajaran. Hal tersebut memiliki kaitan erat dengan metode yang cenderung sering digunakan oleh guru, yaitu dengan metode ceramah. Akibatnya siswa belum secara maksimal dapat mengembangkan potensi dengan aktif. Kecenderungan pembelajaran di kelas lebih memusatkan kepada guru yang aktif daripada siswa yang aktif. Oleh sebab itu, keaktifan belajar siswa perlu ditingkatkan dengan menggunakan metode Group Investigation. Metode penelitian yang digunakan adalah Penelitian Tindakan Kelas (PTK). Penelitian berlangsung selama dua siklus, dari tanggal 7 September 2015 hingga 21 September 2015. Instrumen yang digunakan dalam penelitian antara lain, angket siswa, check list mentor, dan wawancara mentor. Data yang diperoleh dianalisis secara statistik deskriptif sederhana. Validasi data dilakukan oleh guru pamong yang juga selaku guru bidang mata Pelajaran Ekonomi dan Dosen Pembimbing Lapangan. Berdasarkan hasil dari instrumen yang telah digunakan, maka dapat disimpulkan bahwa penerapan Group Investigation dapat meningkatkan keaktifan belajar siswa kelas IX pada mata pelajaran IPS Terpadu. / Based on observation conducted at grade IX SMP ABC, a problem occurred in teaching and learning process which is students were not showing their active behavior in learning process. The activeness has a strong correlation with the method that teacher usually use, which is direct instruction. In the end, students couldn’t maximally develop their potentials actively. Learning process in the classroom tends to focused on the teacher, not the students. By that cause, author needs to increase the activeness of students. For that, Group Investigation Method is used to achieve the research goal, which is increasing student’s activeness. Class Action Research (CAR) is used as research method. Research conducted in two cycles, from September 7th 2015 until September 21st 2015. The subject was students from grade IX in SMP ABC. To gather the right information and holistic, some instruments are used: questionnaire, mentor’s checklist, and interview. Data acquired is analyzed with simple descriptive statistics. Data validation was conducted by partner teacher that also Economics teacher and Field Supervisor. Based on the result of the instruments used, can be concluded that Group Investigation Method can increase students activeness in grade IX in IPS Terpadu Subject.