We examine university students’ motivation and self-efficacy beliefs about proof and proving, i.e., beliefs about personal abilities to understand, construct and present mathematical proofs, as well as their certainty about self-produced proofs. The sample of the study consists of 29 Finnish and Swedish students who were studying mathematics in tertiary level. The results show that the students were highly motivated to learn to understand and construct proofs, but they were more uncertain about their proving skills. Moreover, the study revealed reasons for the uncertainty about proving achievements. Most of the reasons are caused by deficiencies with respect to knowledge of, understanding about or experience from proof and proving.