What do teachers know regarding word problem-solving in middle school? How confident are they in their knowledge? What do they believe is essential for them to know to teach word problem-solving? These three questions led to the current study in which 57 teachers who teach word problem-solving in middle school were examined regarding three factors that may influence the teaching-learning process of the subject: teachers' knowledge (content knowledge and pedagogical content knowledge), their sense of self-efficacy regarding their knowledge, and their beliefs about the knowledge needed to teach word problems. The knowledge was tested according to the theoretical framework laid by Deborah Ball and colleagues (Ball et al. in J Teach Educ 59:389-407, 2008), which defines four knowledge components: common content knowledge, specialized content knowledge, knowledge of content and teaching, and knowledge of content and students. Findings regarding teachers' beliefs show that teachers believe that the most essential knowledge components are specialized content knowledge and knowledge of content and students. Regarding teachers' self-efficacy in their knowledge, it was found that teachers were most confident in their common content knowledge and least confident in their knowledge of content and students. Findings regarding teachers' knowledge show that they had content knowledge (they solved the problems correctly). However, they showed partial knowledge of the other knowledge components, especially in the knowledge of content and students. The study's findings show that teachers' training and coaching need to strengthen the knowledge components, especially specialized content knowledge and knowledge of content and students.