Hasil belajar kognitif siswa pada mata pelajaran Ekonomi di kelas XI IPS di salah satu sekolah Kristen di Makassar tidak mencapai nilai KKM. Salah satu faktor penyebabnya ialah metode yang digunakan tidak cukup menjawab karakteristik dan kebutuhan siswa. Hal tersebut mendorong guru melakukan penelitian dengan menerapkan model pembelajaran kooperatif tipe group investigation meningkatkan hasil belajar kognitif siswa, serta ingin mengetahui cara penerapan model pembelajaran kooperatif tipe group investigation dalam meningkatkan hasil belajar kognitif siswa kelas XI IPS. Metode penelitian yang digunakan ialah Penelitian Tindakan Kelas (PTK) model Robert P. Pelton. Penelitian ini dilaksanakan di salah satu sekolah kristen di Makassar pada siswa kelas XI IPS dengan jumlah 23 orang, pada tanggal 8 Agustus 2018-28 Februari 2019. Peneliti menggunakan lembar tes tertulis, RPP (Rancangan Perencanaan Pembelajaran), lembar umpan balik guru mentor, lembar observasi checklist dan jurnal refleksi untuk mengumpulkan data. Analisis data dilakukan secara deskriptif kualitatif. Hasil dari penelitian ini menunjukkan bahwa model pembelajaran kooperatif tipe group investigation dapat meningkatkan hasil belajar kognitif siswa kelas XI IPS secara presentase yaitu sebanyak 70 % siswa lulus KKM. Langkah – langkah model pembelajaran tipe group investigation yang dilakukan untuk meningkatkan hasil belajar kognitif siswa, ialah: team, identification, planning, investigation, final project, presentase dan evaluation./ Cognitive learning outcomes of grade XI IPS students in economy subject at one of the Christian schools in Makassar did not meet the minimum passing criterion. One of the factors is the method used was not fit enough with students’ characteristics and needs. That thing pushes teacher to conduct research by implement the cooperative learning type group investigation to improve students’ cognitive learning outcomes, also to know how the implementation can improve grade XI IPS students’ cognitive learning outcomes. The method used in this research is Classroom Action Research (CAR) model proposed by Robert P. Pelton. This research was done at one of Christian schools in Makassar with 23 students of grae XI IPS, on 8th August 2018 to 29th February 2019. The researcher utilized several instruments, namely, test, lesson plan, mentor feedback form, observational checklist form, and journal reflection to collect the data. The data are analayzed qualitatively. The results of this research show that the copperative learning type group investigation can improve grade XI IPS students’ cognitive learning outcomes, which is 70% of the students exceed the minimum passing criterion. The steps of the group investigation type of learning model which is done to improve students’ cognitive learnig are team, identification, planning, investigation, final project, presentation, and evaluation.