The aim of the current study is to examine the level of middle school students' mathematical metacognitive awareness and mathematics problem-posing self-efficacy and to compare their related awareness and self-efficacy according to the variables of gender, grade level, socio-economic status, and mathematics achievement. This research is a relational screening model designed by causal comparison approach. The study was carried out on 462 students selected by random sampling method among middle school students studying in the 5th, 6th, 7th and 8th grades in two public schools. Data were collected with the 'Personal Information Form", "Problem Posing Self-Efficacy Scale", and "Mathematical Metacognition Awareness Scale". The independent sample t-test, one-way analysis of variance, and Pearson Product Moment Correlation Coefficient were applied in the data analysis. As a result of the research, it was found that the level of the students' mathematical metacognitive awareness and problem-posing self-efficacy were high. It was determined that the mathematical metacognitive awareness and problem posing self-efficacy of the students did not differ significantly with regard to grade and socio-economic status of the family. Furthermore, a statistically significant difference was found between the students’ mathematical metacognitive awareness and problem posing self-efficacy regarding their gender and mathematics achievement. Activities aimed at developing or increasing mathematical metacognitive awareness and problem posing self-efficacy of students should be prepared by paying attention to gender and mathematics achievement differences.