Penelitian ini bertujuan untuk mengetahui bentuk-bentuk atau macam-macam kenakalan siswa SMP di Kota Yogyakarta, dan untuk mengetahui perbedaan intensitas kenakalan siswa SMP Negeri dan SMP swasta. Populasi penelitian ini adalah siswa SMP kelas 9, baik negeri maupun swasta sebanyak 1624 siswa dengan sampel penelitian 216 siswa. Sampel sekolah diambil 25% sehingga untuk SMP negeri diperoleh 4 sekolah (25%x16) dan untuk SMP swasta diperoleh 6 sekolah (25%x24). Sampel siswa untuk SMP negeri diambil 108 Siswa dan untuk SMP Swasta diambil 108 siswa. Pengambilan sampel dengan teknik proportional random sampling. Pengumpulan data dengan angket dan wawancara terbatas (perwakilan siswa). Analisis data dengan tabulasi frekuensi dalam bentuk angka dan persentase. Besar kecilnya persentase dalam tabel digunakan sebagai dasar pengambilan kesimpulan. Hasil penelitian menemukan; (1) pulang ke rumah terlambat 81,01%, (2) berbohong kepada orang tua/orang lain 68,52%, (3) berbuat ulah sehinga guru marah 62,50%, (4) menonton film porno 11,69%, (5) penggunaaan uang SPP untuk kepentingan lain 9,26%, (6) sebagai kelompok geng 8,80%, (7) terlibat tawuran 8,33%, (8) menyontek saat ulangan 6,94%, (9) mengganggu orang lewat 5,56%, (10) memalsu tanda tangan presensi 5,56%, (11) membaca buku porno 3,24%.Kata kunci: kenakalan siswa, bentuk kenakalanAbstractThis study aims to determine the forms or kinds of delinquency junior high school students in the city of Yogyakarta and to determine differences in the intensity of student delinquency at public junior high school and private junior high school. The study population was junior high school students of class 9, both public and private as much as 1624 students with 216 students study sample. Samples were taken 25% of school so as to public junior high school earned 4 (25% x16) and for private junior high school earned 6 (25% x24). Samples taken public junior high school students to 108 students and for private junior high school taken 108 students. Sampling with proportional random sampling technique. Collecting data by questionnaires and interviews are limited (student representative). Tabulation of data analysis with frequency in the form of numbers and percentages. The size of the percentages in the table are used as the basis for making conclusions. Results of the study successively discovered; (1) come home late 81.01%, (2) lying to parents/others 68.52%, (3) do act so that the teacher angry 62.50%, (4) watch porn 11.69%, (5) the use of tuition fees for the benefit of another 9.26%, (6) as gangs 8.80%, (7) involved brawl 8.33%, (8) cheat when replay of 6.94%, (9) annoy passers 5.56%, (10) forging signatures presence of 5.56%, (11) reading pornographic 3.24%.Keywords: student misbehavior, delinquency form