Children's view on the peer context in their classroom may differ from that of other informants, but no measure systematically examines children's own view. Therefore, we developed the Classroom Peer Context Questionnaire (CPCQ) and evaluated its reliability, validity, and stability in two studies. In Study 1, 464 children (Mage = 10.8 years, 53.2% girls) from 18 Grade 5 classrooms participated in 2 waves of data collection. In Study 2, 1538 children (Mage = 10.6 years, 47.2% girls) from 59 Grade 5 classrooms participated in 3 waves of data collection. Exploratory factor analyses in Study 1 revealed 5 dimensions labeled comfort, cooperation, conflict, cohesion, and isolation. Confirmatory factor analyses in Study 2 supported these 5 dimensions. Study 2 also demonstrated good reliability, validity, and stability for each dimension. Researchers and professionals in schools may use the CPCQ to obtain reliable and quick information on how children perceive the peer context in their classroom.