This study aims to determine how Christian Education (CE) in the family and social environment of students, and its contribution to the formation of student character. The place where the research was carried out was the private high school GKPI Padang Bulan Medan. The study population was 104 people, while the sample was 30 people. The instrument used for this research was a questionnaire. Based on the results of the study, it was found that there was a contribution of CE in the Family to Character Building at the zero level ry1 = 0.510, there was also a contribution between the Student Social Environment (X2) to the Character Building (Y) at the zero level ry2 = 0.411 and there was a joint contribution between CE in the Family and Social Environment of Students on the Formation of Student Character (1,293). Four characters are described as the character traits of Christianity, namely; Trust completely in God, Not vengeful, Happy to pray, Think rationally. Therefore, parents should continue to provide examples and teaching at home to help shape children's character. Teachers in schools are also to set an example in giving character examples to students.Penelitian ini bertujuan untuk mengetahui bagaimana PAK dalam keluarga dan lingkungan pergaulan siswa memberi kontribusi terhadap pembentukan karakter siswa. Tempat penelitian dilakukan di SMA Swasta GKPI Padang Bulan Medan. Populasi penelitian sebanyak 104 orang sedangkan sampel sebanyak 30 orang. Instrumen yang digunakan dalam penelitian ini adalah angket. Berdasarkan hasil penelitian ditemukan adanya kontribusi PAK dalam Keluarga terhadap Pembinaan Karakter pada tingkat nil ry1 = 0,510, terdapat pula kontribusi Lingkungan pergaulan Siswa (X2) terhadap Pembinaan Karakter. (Y) pada taraf nol ry2 = 0,411 dan ada kontribusi bersama PAK dalam Keluarga dan Lingkungan Sosial Siswa terhadap Pembentukan Karakter Siswa (1,293). Empat karakter yang digambarkan sebagai karakter agama Kristen, yaitu; Percaya sepenuhnya pada Tuhan, Tidak dendam, Senang berdoa, Berpikir rasional. Oleh karena itu, orang tua hendaknya terus memberikan teladan dan pengajaran di rumah untuk membantu membentuk karakter anak. Guru di sekolah juga harus memberi contoh dalam memberikan contoh karakter kepada siswa.