According to expectancy-value models, two important motivational constructs are task value and self-efficacy expectations. As students work intensively on mathematical problems in the classroom, teachers need the competence to judge whether students value solving the problem and how confident they are that they will succeed. However, not much is known about the mechanisms behind teachers' judgments concerning students' motivation. The goal of the present study was to answer the following research questions: (a) How do preservice teachers rate their "own" task value and self-efficacy for modelling, word, and intramathematical problems? (b) Are there differences in preservice teachers' diagnostic judgments concerning "school students'" task value and self-efficacy for modelling, word, and intramathematical problems? (c) Do preservice teachers' "own" task value and self-efficacy for modelling, word, and intramathematical problems differ from preservice teachers' judgments of "school students'" task value and self-efficacy? A total of 182 preservice teachers were asked about the value of 12 problems, their confidence in solving the problems, and how hypothetical ninth graders would judge these constructs. Preservice teachers' ratings of their "own" perceptions regarding both constructs were lower for modelling problems than for other problems. When judging "school students'" motivation, ratings of both constructs were higher for word problems. Preservice teachers' ratings of their "own" motivation were significantly higher across all types of problems than their judgments of "school students'" perspectives. A positive correlation between preservice teachers' own motivation and their judgments of "school students'" motivation indicates the importance of teachers' perceptions of their own motivation to solve mathematical problems for diagnostic judgments.