This study aimed to determine students' misconceptions related to vaporization and vapor pressure. In order to fulfill this aim, open-ended diagnostic questions and semi-structured interviews were used. The diagnostic questions were administered to 70 third-year students enrolled in the Primary Science Teacher Training Department at Ataturk University in Turkey. In addition, 12 students were interviewed in order to clarify their written responses and to further probe students' conceptual understandings of the questions asked in the test. Seven different misconceptions were identified. The results have implications for tertiary-level teaching, suggesting that a substantial review of teaching strategies is needed.