Pada proses pembelajaran kelas IV pada salah satu SD di Jakarta Barat, ditemukan adanya masalah pada sikap kerja sama siswa dalam kelompok. Kurangnya kerja sama siswa dalam kelompok mengakibatkan kegiatan kelompok tidak berjalan dengan maksimal. Berdasarkan hal tersebut, peneliti melakukan penelitian yang bertujuan untuk mengetahui apakah penerapan model pembelajaran kooperatif tipe Numbered Heads Together (NHT) dapat meningkatkan kerja sama siswa dan bagaimana langkah-langkah penerapan NHT dapat meningkatkan kerja sama siswa. Metode Penelitian Tindakan Kelas (PTK) yang digunakan adalah model yang dikembangkan oleh Robert P. Pelton. Subjek penelitian yaitu 25 siswa kelas IV. Penelitian dilakukan pada tanggal 14 Agustus 2018 sampai 26 September 2018. Sumber data yang digunakan dalam penelitian yaitu RPP, jurnal refleksi, umpan balik mentor, lembar observasi mentor, angket siswa, dan rubrik kerja sama. Hasil penelitian menunjukkan adanya peningkatan kerja sama siswa dalam kelompok dengan menerapkan langkah-langkah NHT. Dengan demikian, dapat disimpulkan bahwa model pembelajaran kooperatif tipe Numbered Heads Together yang diterapkan berdasarkan langkah-langkah penerapan NHT, dapat meningkatkan kerja sama siswa dalam kelompok kelas IV pada salah satu SD di Jakarta Barat. / In the fourth grade learning process at one elementary school in West Jakarta, it was found that there was a problem in the attitude of cooperation between students in the group. The lack of cooperation between students in the group resulted in group activities not running optimally. Based on this, the researchers conducted a study that aimed to determine whether the implementation of the Numbered Heads Together (NHT) type of cooperative learning model can enhanced the student cooperation and how the steps for implemented NHT can enhanced student cooperation. The Classroom Action Research Method (CAR) used a model developed by Robert P. Pelton. The research subjects were 25 fourth grade students. The study conducted on August 14, 2018 until September 26, 2018. The data sources used in the study were lesson plans, reflection journals, mentor feedback, mentor observation sheets, student questionnaires, and collaboration rubrics. The results of the studies indicate an enhancement in student cooperation in groups by implemented NHT measures. Thus, it concluded that the Numbered Heads Together type of cooperative learning model based on the steps of implemented NHT, can enhanced the cooperation of students in class IV in one elementary school in West Jakarta.