The advent of problem-based assessment has opened the question of whether or not conventional approaches to assessment are truly a representative of students' knowledge (Lampert, 2001). In an attempt to find out about the suitability of problem-based tests in evaluating student-teachers' knowledge of teaching English, a problem-based test was designed and administered to 33 MA students who were selected through the quota approach at Payame Noor University. Comparison of the results of the problem-based test and conventional test through paired-samples t-test revealed that teacher-students gained higher scores in the conventional tests; however, the results of the semi-structured interview with the participants revealed that they considered problembased test a true measure of their knowledge and favored it over conventional assessment due to its relevance to content and context of the course, its motivating nature, and its dynamic structure. This study can have pedagogical implications for language teachers and material developers.