YGS-LYS or Yükseköğretime Geçis Sınavı-Lisans Yerleştirme Sınavı (English: Higher Education Examination-Undergraduate Placement Examination), also known ÖSS or Öğrenci Seçme Sınavı (English: Student Selection Examination), is a standardized test for the admission to higher education in Turkey administered by ÖSYM. Within the Turkish education system, the only way to enter a university is through this exam. 1,510,000 high school graduates took the exam in 2006. It is a multiple choice exam (5 options).
ÖSS was first applied in the late 1960s. Before that year, each university selected its students via some criteria. However, with the increasing number of youth and the overloaded applications, the universities gathered and founded "Yüksekögretim Kurulu", the Higher Education Council, and a subdivision named ÖSYM, "Student Selection and Placement Center". The name of the exam was decided to be ÖSS, Student Selection Examination. In 1974, the format of the exam was changed. In 1980, another big change took place: the number of the exams were increased to two, namely the ÖSS and ÖYS. If a student did not achieve the specified grade in ÖSS, he did not have the right to enter ÖYS, and thus, lost his chance to be accepted to a university. This system continued until 1999, the date when ÖYS was dropped and only ÖSS was left, with the same format and same questions.