The importance of proof for doing and learning mathematics is well recognized, as evidenced by the extensive body of literature on proof as well as the increased emphasis placed on proof in the policy documents. However, research typically shows that students at all grade levels struggle with proof and often hold narrow conceptions (or even misconceptions) of proof. Further, despite the extensive research base on students’ conceptions of proof, less is known about how students’ conceptions of proof relate to their experiences in classrooms. Thus, an important need is to better understand how to positively influence students’ conceptions of proof through instruction. To address this need, I sought to examine how students’ views and understandings about proof and proving are related to classroom factors. Hence, I conducted an in-depth case study of one high school mathematics class, collecting a series of classroom observations and individual interviews with the students and their teacher in order to examine the students’ conceptions of proof in relation to their teacher’s conceptions of proof and their classroom experiences. By focusing on the interview data, I first examined to what extent and in what ways the students’ conceptions of proof resembled or differed from their teacher’s conceptions of proof. The results indicated a close alignment between the students’ and their teacher’s conceptions, suggesting that the students have appropriated their teacher’s values of proof. I then examined the ways in which the classroom factors might have supported the close alignment between the students’ and their teacher’s conceptions. Specifically, I discuss how the curricular materials and the teacher (through her instructional emphases and practices) supported the students’ notions of proof, including their views about the roles of proof. I also discuss how the classroom factors may have fostered the development of the deductive proof scheme, while discouraging the development of the authoritative and empirical proof schemes. In conclusion, the study offers evidence that students can develop robust conceptions of proof if the learning environment is conducive to sharing and justifying mathematical ideas where the teacher values proof as an important aspect of doing and learning mathematics.