Studies of psychological misconceptions have often used tests with methodological shortcomings, unknown psychometric properties, and ad hoc methods for identifying misconceptions, creating problems for estimating frequencies of specific misconceptions. To address these problems, we developed a new test, the Test of Psychological Knowledge and Misconceptions, administering it to a sample of 162 graduate and undergraduate psychology students and to a second sample of 173 undergraduate psychology majors. Results revealed high consistency in item response frequencies across samples, allowing identification of specific misconceptions. We found that certainty ratings of the correctness of more frequently endorsed misconceptions were significantly higher than misconceptions endorsed less frequently while some other items endorsed much less frequently also showed higher certainty. Our findings bear implications for dispelling erroneous but confidently held claims in psychology courses.