This paper examines Grade 10 students' conceptions of proof in a secondary school in Singapore. Using a purposive survey of 9 mathematical items, proofs by 8 students for two items, one on Number and Algebra and another on Geometry and Trigonometry, were coded using Harel's proof schemes. The findings show that the students' proofs for the two questions displayed a range of proof schemes, except the authoritative scheme. With the exception, of the perceptual scheme, the predominance of other schemes was item specific. It was also apparent from the proofs written by the students that they struggled to articulate their arguments using correct mathematical language.