The present study investigated 8(th) grade students' perceptions of actual and preferred constructivist science learning environments. Data were collected from 1152 students attending public elementary schools in Ankara using the Constructivist Learning Environment survey (CLES). The CLES consists of two forms which are "Actual" and "Preferred". While actual form assesses the current learning environment of the classroom and the preferred form assesses the students' preferences about the learning environment. Results showed that students' scores on the preferred form were significantly higher than those of the actual form on each scale (p<0.05). Students tended to prefer more constructivist learning environments in which they have more opportunities to relate science with the real world, communicate in the classroom, take role in the decision making process of what will go on in the lesson to be more beneficial for them, question what is going on in the lesson freely and experience the formulation of scientific knowledge.